Green bean plant disease

Signs of bean rust: the light-coloured spots on the upper and lower leaf surfaces.
Photo: Bill Kerr

  • 2shares
  • Share0
  • Tweet0
  • Share0
  • Print2
  • Email0

Breeders now use two resistant genes in combination to ensure sufficient rust resistance. Highly effective systemic products are also available to make the disease easier to control. The first signs of rust are light-coloured spots, mainly on the underside of the leaves. These develop into pustules. The entire plant is affected, however, so the pods may also be unmarketable.

Usually, all that is required for the disease to appear is a susceptible variety and mild or cool weather conditions. On the Highveld, the disease first appears between the new year and winter. In subtropical areas, it becomes more severe towards spring, but appears throughout the growing season.

The fungus enters the plant through the stomata. After five days, the white spots appear. The brown pustules appear five to 10 days later. The spores released are spread mechanically and by wind. As soon as you see the light spots, spray a suitable systemic product, with a repeat application 10 days later. This should control the disease.
Angular leaf spot
This occurs sporadically, usually after a prolonged rainy period. The name describes the disease rather well: brown spots develop on the leaves and fill in the spaces between the veins, creating angular spots. The pods are also infected. The causal organism is Isarioposis griseola. This can overwinter in plant debris and can also be transmitted by seed, although this is seldom the case nowadays. The spores do not last long on infected debris. If the crop residue is fully decomposed it will be safe.

When infected leaves are turned over, you will see small black spots within the lesions. These are the spore-forming fruiting bodies.

Angular leaf spot can spread rapidly through a crop, so spray with a suitable systemic fungicide as soon as the first symptoms appear. Resistant green bean varieties are also available, with quite a difference in susceptibility between varieties in a trial when the disease appears.

Anthracnose
This is a highly destructive disease caused by the Colletotrichum lindemuthianum bacterium, which favours cool, wet conditions. It is brought in by infected seed and the disease manifests as reddish brown circular spots with light centres. Similar spots develop on the pods, which also become sunken.

I have come across anthracnose only once in the past 35 years. That was when viewing trials at a processor where a seed company had submitted a variety for evaluation. It was infected with the pathogen; all other varieties were clean. The disease is no longer a major threat as infected seed is rarely sold by seed companies.

If you do find it in your crop, ask your crop chemical representative for a fungicide to spray and keep that land free from beans for two years.

Sclerotinia
Sclerotinia sclerotiorum affects many different crops, so is fairly common. It shows up as a cotton wool-like fungus spreading throughout the plant and causing the tissue to become soft and then rot. Dark-coloured bodies form in this mass and harden.

Next season, small mushrooms develop from these sclerotia when there is a period of cool, rainy weather. When the weather clears, the mushrooms release millions of spores. These travel through the air and germinate on damaged tissue or even flowers that have started to wither after pollination.

Sclerotina can be very destructive, and it is best to avoid planting beans the year following a crop on which the disease was observed.

Top 17 Problems All Green Bean Growers Must Overcome

Green beans (Phaseolus vulgaris) are among the most common vegetables people grow in the home garden. They produce a fine crop within sixty days, making them faster than many vegetable crops, and the beans can be eaten fresh, frozen, or canned.

When it comes to green beans, you can opt for pole beans, which grow on trellises, fences, or poles; or bush beans, which are compact varieties that require no support. I’ve tried both, but I prefer pole beans because they produce a greater overall yield for a longer period of time. (And my kids like to hide among the trellises.) Bush beans are a bit like determinate tomatoes. They produce a big yield within a few weeks, making them ideal if your only goal is to harvest beans for processing.

Most years, I’ve had no trouble with growing beans. On the odd occasion, though, I’ve experienced problems with growth, disease, and pests. Below, you’ll find information on the most common bean problems and how to avoid or fix them.

Seeds don’t germinate. Beans are warm-season crops, and they don’t like cold, wet soil. Wait to plant them until daytime air temperatures are at least 70 degrees. Avoid planting them too deeply, especially in the spring when the soil is still cold. Plant them no more than one inch deep in the spring. If you have a short growing season, try building raised beds, which warms the soil earlier in the spring so you can plant sooner. For fall plantings, you can plant them up to two inches deep, especially if your soil is dry. Water the soil frequently so it stays moist but not soggy one inch beneath the surface. In dry soils, the seeds won’t germinate. Forget the old-time advice of soaking bean seeds before planting them. Bean seeds do have a hard seed coat, but they don’t need to be soaked. Doing so often cracks the seeds and damages them so they rot.

Young seedlings have dark, water-stained spots on their leaves or collapse. This condition is known as damping off and is caused by high humidity levels and cold, damp soils. Remove the plants and try again in a few weeks when the soil is warmer.

Young seedlings are stunted and don’t recover. Again, this is caused by cold temperatures. The seedlings might eventually start growing, but you’re probably better off taking them out and replanting them in warm soil.

The seedlings fall over and die. Check the stems. If the stems seem as if they were cut off, it’s probably because they were. Cutworms have been at work in your garden. Till the soil to destroy them and remove any garden debris and weeds, which provides shelter for the pests. Place cardboard collars around young seedlings as soon as they emerge from the soil. Bury the collars three inches deep in the soil.

Deformed seedlings that lack leaves. Corn seed maggots have probably been feeding on your green beans. Remove the plants and cultivate the soil to destroy the pests. Replant in warm weather.

Yellowed, distorted leaves. Thrips, tiny black or brown insects, have been feeding on the leaves. These insects generally move on in a week or two and the plants recover on their own.

Large holes in the leaves. Bean leaf beetles have likely been at work in your garden. These small orange or red beetles can cause considerable damage. Handpick and destroy any you see. In the future, till the soil to at least six inches to destroy the larva. Spread a floating row cover over the beans immediately after planting to exclude the pests.

Use this as a potting medium, insecticide, or even a household substance…without dangerous chemicals!

Curled or yellowed leaves. You might also notice a sticky substance on the leaves and ground, or a black powder, which is sooty mold. These symptoms indicate an aphid invasion. The tiny brown, red, or green insects damage beans by sucking the sap from the leaves and stems. They usually move on in a few weeks. In the meantime, try spraying the undersides of the leaves with a stream of water or coat the leaves with insecticidal soap. Ladybugs eat aphids, so you might be able to control them with these beneficial insects. Ants often farm aphids and eat the honeydew, so control the ants with ant barriers, and you’ll likely control the aphids too.

Skeletonized leaves. If nothing is left of the leaves but the veins and stems, you probably have Japanese beetles or Mexican bean beetles. Handpick these pests and drop them in a bucket of soapy water. To prevent their appearance, cultivate the soil to destroy any overwintering larva. Install floating row covers after planting.

White stippling or speckles on the upper sides of the leaves. The edges of the leaves may become yellowed or scorched. Leafhoppers, like aphids, are tiny insects that suck the juices from the beans. Prevent them with floating row covers. Treat infested plants with insecticidal soap.

Gray or white mold on the leaves, stems, and pods. This condition, white mold, is most prevalent in warm, humid conditions. Once beans are infected, the condition is fatal. Wet leaves can spread the disease, so use soaker hoses instead of overhead sprinklers. Avoid working in the garden while it’s wet. Space the beans so air circulates freely, and rotate crops so beans don’t grow in the same place year after year.

Water soaked spots on the leaves. You might also notice stunted growth or a white mold. This is caused by bacterial wilt, a fatal disease most prevalent in wet soils. Add compost and peat moss to improve drainage and avoid overwatering. Cucumber beetles can also spread the disease. Handpick them or treat them with rotenone. Again, floating row covers can keep them out.

Stunted, weak plants with yellow leaves. You may also notice red spots near the stems. These symptoms are usually caused by fusarium wilt, a disease that can live in the soil. Remove infected plants and rotate crops. If the disease continues, try solarizing the soil. Spread a clear sheet of plastic over the soil during the hottest period of the summer. Secure it tightly to the ground with rocks or pins. Leave it in place for four to six weeks. The high temperatures will kill the pathogens that cause this disease.

Shriveled water pods and brown to reddish streaks on the leaves and pods. Anthracnose is a fungal disease, which is spread through wet leaves. Use soaker hoses instead of overhead sprinklers and avoid working in a wet garden.

Stunted plants and mottled leaves. Mosaic virus is a fatal bean disease. If you notice these symptoms, remove the plants immediately and discard them. Rotate bean crops and choose disease-resistant varieties in the future.

Stunted plants with purple stems and veins. The leaves may also curl or grow downward. These symptoms indicate curly-top virus, a disease spread by leafhoppers and aphids. Remove infected plants. In the future, remove all weeds and garden debris and spray leaves with insecticidal soap to treat the insect pests.

Flowers not setting fruit. When nighttime temperatures drop below 55 degrees or daytime temperatures rise above 90, the flowers might drop without pollinating. Spread floating row covers over the plants during cold weather. In hot weather, your only recourse is to wait until temperatures cool. The beans will start producing again.

Common blight of beans

Note Number: AG0557
Published: December 1999
Updated: September 2010

Caused by

Xanthomonas campestris pv. phaseoli

Introduction

Common blight, caused by a bacterium which infects foliage, pods and seed is very destructive and can cause major losses in yield.

Symptoms

Symptoms initially appear on leaves as water soaked, often angular shaped spots and gradually grow to form large-brown spots of dead tissue, often surrounded by a very narrow zone of yellow tissue. Spots can form at the margins and interveinal regions. In severe infections, the plant appears burnt and dead leaves remain attached.

Spots on pods are generally circular, slightly sunken, water-soaked and dark green in colour. As spots age they turn dark red-brown in colour and under extremely humid conditions are covered with bacterial ooze.

Symptoms of common blight appear similar to halo blight, but halo blight has leaf spots with large, pale yellow margins.

Bean plants showing common bacterial
blight symptoms caused by Xanthomonas
campestris pv. phaseoli in the field.
Howard F. SchwartzBean leaflets showing common bacterial
blight symptoms caused by Xanthomonas
campestris pv. phaseoli. Howard F. Schwartz

Biology

Disease cycle

Bacteria enter plants through wounds or natural openings. It takes 10-14 days from initial infection for new bacteria to be released.

Survival

The bacterium can survive either inside the seed or on the seed surface. Tolerant varieties may harbour the bacterium. It over winters on infected plant debris, especially on residues near the soil surface. The bacterium can also survive on the surface of volunteer beans, weeds and intercropped plants without showing any symptoms.

Dispersal

Contaminated seed is the major means of dispersal of the bacterium. It is also spread by plant to plant contact, especially when wet and by water splash from rain or overhead irrigation. It can be transported in soil, irrigation water, by insects, animals and people.

Environmental conditions

Development of the disease is favoured by warm-humid weather, with or without rain and temperatures of 28-32 °C.

Host range

French and mung beans.

Control

  • Use disease-free seed.
  • Plant tolerant or resistant cultivars.
  • Use a crop rotation of two or more years between bean crops.
  • Eliminate alternate hosts such as volunteer beans and weeds.
  • Use a registered bactericide spray if weather conditions favor disease development.
  • Avoid overhead irrigation.

Further References

Persley, D., Cooke, T. and House, S. (2010). Diseases of vegetable crops in Australia. CSIRO Publishing, 292p.

Koike, S.T., Gladders, P. and Paulus, A.O. (2007). Vegetable diseases, a colour handbook. Mason Publishing, 448p.

Howard, F. S., James, R. S., Robert, H., and Robert, L. F. (2005) Compendium of Beans diseases. APS Publishing, 120p.

Contact/services available from DEPI

For effective pest and disease control, correct diagnosis is essential. Phone Crop Health Services on (03) 9032 7515 or fax (03) 9032 7604.

For further information on registered chemicals, phone the DEPI Customer Service Centre on 136 186.

Acknowledgements

This Agriculture Note was developed by Elizabeth Minchinton, Knoxfield in December 1999.

It was reviewed by Elizabeth Minchinton, BioSciences Research in September 2010.

ISSN 1329-8062

Published and Authorised by:
Department of Environment and Primary Industries
1 Spring Street
Melbourne, Victoria

This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968.

The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication

Bean & Southern Pea Diseases

Beans and Southern peas, including cowpeas, black-eyed peas and crowder peas, are commonly affected by many diseases in the home garden. Many of these problems can be successfully avoided by following recommended cultural practices.

  • Plant certified seed or seed of known high quality that has been treated with a fungicide.
  • Select resistant varieties for planting.
  • Rotate the location in which beans are planted in the garden.
  • Plant beans in a well-drained area and avoid overhead watering.
  • Remove bean debris from the garden after harvest, since this is where some disease-causing agents can survive the winter.

More information on successfully growing beans and Southern peas is available in HGIC 1302, Bush & Pole Type Snap Beans, andHGIC 1319, Southern Pea.

Anthracnose

Bean pods with black, sunken lesions or reddish-brown blotches most likely have anthracnose, a fungal disease caused by Colletotrichum lindemuthianum. Black, sunken lesions about ½ inch in diameter develop on stems, pods and seedling leaves (cotyledons) but are most prominent on pods. Lesions may develop salmon-colored ooze, and the veins on lower leaf surfaces turn black. On lima beans, symptoms are sooty- appearing spots on leaves and pods. Anthracnose develops primarily during the spring and fall when the weather is cool and wet, and not during our hot, dry summers. Lima beans are particularly susceptible.

Prevention & Treatment: Prevent this disease by using certified disease-free seed for planting and removing all plant debris after harvest. Anthracnose can survive in the soil for two years on plant debris or be brought to the garden on infected seeds. Do not plant bean seeds in an area that had disease for two to three years. Avoid overhead watering and avoid splashing soil onto the plants when watering. Fungicide sprays of fixed copper are the only recommended chemical that can be used on lima beans for anthracnose control. Either copper fungicides or chlorothalonil can be used on snap or pole beans. Wait seven days between spraying with chlorothalonil and harvest, and one day between spraying a copper fungicide and harvest. Chlorothalonil and copper fungicides both give fair control of anthracnose. Spray chlorothalonil at 7-day intervals and copper fungicides at 10-day intervals. Apply according to directions on the label.

Bean Root Rots

Many fungi, including Rhizoctonia solani, Pythium species and Fusarium solani, form species phaseoli, live in the soil and will infect young seedlings or the seeds of bean plants. Seedlings fail to emerge after planting when the seeds rot in the soil or young seedlings may be stunted. Plants are usually affected slightly above or below the soil line with a watery soft rot. Roots of the plant usually die and the leaves turn yellow.

Prevention & Treatment: Do not plant beans in low-lying, poorly drained areas. Plant beans on raised beds. Plant after the soil has warmed to 69 °F at a 4-inch depth. Reduce disease buildup in the soil by rotating locations in the garden where you plant bean or pea with other vegetables. Try to avoid injury to the root system, which often occurs during planting, through cultivation or due to a large population of nematodes in the soil. Remove crop debris immediately after harvest. Plant seeds previously treated with captan (a fungicide).

Table 1. Some Disease Resistant Varieties for South Carolina.

Variety Resistant
Lima Bean ‘Jackson Wonder-AR’ Partially resistant to anthracnose.
Pole Bean ‘Kentucky 191’ Resistant to rust.
Snap Bean ‘Derby,’
‘Provider’
Resistant to Bean common mosaic virus.
Southern Pea ‘Mississippi Silver,’
‘Mississippi Purple’
Resistant to Black-eyed cowpea mosaic virus and Fusarium wilt.

Rust

Bean rust is mainly a disease of bean leaves that causes rust-colored spots to form on the lower leaf surfaces. Severely infected leaves turn yellow, wilt, and then drop off of the plant. Stems and pods may also be infected. This disease is caused by the fungus Uromyces appendiculaters. It affects most types of beans under humid conditions.

Prevention & Treatment: The fungus survives the winter in the soil, on plant debris and even on poles used the previous year. In gardens where rust has been severe, crop rotation is important. As plants begin to bloom, sulfur or chlorothalonil can be sprayed weekly on snap and green beans only. Do not apply chlorothalonil to lima (butter) beans. Wait seven days between spraying and harvest when using chlorothalonil on beans, and 14 days on Southern peas. Chlorothalonil gives excellent control of rust, and sulfur gives good control. Spray chlorothalonil at 7-day intervals and sulfur at 10 to 14-day intervals. Apply chemicals according to directions on the label.

Bacterial Blights

There are two widespread bacterial blights that affect most types of beans, common blight (Xanthomonas campestris pathovar phaseoli) and halo blight (Pseudomonas syringae pathovar phaseolicola). The stems, leaves and fruits of bean plants can be infected by either disease. Rain and damp weather favor disease development.

Halo blight occurs primarily when temperatures are cool. Light greenish-yellow circles that look like halos form around a brown spot or lesion on the plant. With age, the lesions may join together as the leaf turns yellow and slowly dies. Stem lesions appear as long, reddish spots.

Leaves infected with common blight turn brown and drop quickly from the plant. Common blight infected pods do not have the greenish-yellow halo around the infected spot or lesion. Common blight occurs mostly during warm weather.

Prevention & Treatment: Both of these diseases come from infected seeds. The diseases spread readily when moisture is present. Avoid overhead watering and do not touch plants when the foliage is wet. The bacteria can live in the soil for two years on plant debris. Do not plant beans in the same location more frequently than every third year. Buy new seeds each year. Copper fungicides can be applied at ten day intervals. Wait one day between spraying and harvest.

Mosaic Viruses

Mosaic viruses in which the leaves show sharply defined patches of unusual coloration may occur in beans. The causal agents of these symptoms may be nutrient imbalance or herbicide injury or result from infection by one of several viruses. In South Carolina viruses commonly found infecting beans are Bean yellow mosaic virus, Bean common mosaic virus and Clover yellow vein virus. Southern peas can be infected by Cowpea aphid-borne mosaic virus, Bean common mosaic virus and several others. It is not possible to distinguish between the viruses based on symptoms alone. Laboratory tests (ELISA) are required to identify the viruses and confirm that they may be responsible for the mosaic symptoms.

Prevention & Treatment: There are no recommended chemical controls for these problems. Many of these viruses are transmitted by aphids and are also transmitted through seed. For this reason it is unwise to save seeds from year to year. Reflective plastic mulch may reduce disease by disorienting aphids and thus preventing them from feeding on the bean crop. Control weeds in and near the garden, which may bring aphids into the garden.

Powdery Mildew

Leaves are covered with patches of a whitish to grayish powdery growth. This disease is caused by the fungus Erysiphe polygoni. New growth appears contorted, curled or dwarfed and may turn yellow and drop. Pods are dwarfed and distorted. This is mostly a problem on fall beans. Powdery mildew is spread by wind and rain.

Prevention & Treatment: Avoid crowding plants by allowing adequate space between rows. When the disease is first noticed, sprays or dusts of sulfur are recommended for use on snap and green beans, as well as on Southern peas. Sulfur gives good control of powdery mildew. Apply at 10 to 14-day intervals. Do not use sulfur on young plants, and avoid use on plants if temperatures are over 90 ºF. Apply chemicals according to directions on the label.

Cercospora Leaf Spot

This fungal disease, caused by Cercospora species, occurs primarily on the lower leaves of plants as irregular, tan spots. Severe infection causes excessive leaf drop and stunting of the plant. Infection is worse during periods of extended rainfall, high humidity and temperatures between 75 to 85 °F.

Prevention & Treatment: Use disease-free seed for planting. Remove all debris in the garden after harvest. Do not plant beans in the same area for two to three years. There are no resistant varieties for this disease in the home garden. Chlorothalonil sprays give very good control, and sulfur sprays give fair control of Cercospora leaf spot. Do not apply chlorothalonil to lima (butter) beans. Wait seven days between spraying and harvest when using chlorothalonil on beans, and 14 days on Southern peas. Apply chemicals according to directions on the label.

Watery Soft Rot

Small, soft, watery spots that are caused by the fungus Sclerotinia sclerotiorum occur on the stems, leaves and pods of beans. These spots enlarge rapidly under cool, moist conditions, and run together, girdling the stem. Infected pods turn into a soft, watery mass, before dying out and turning brown. Soon infected areas are covered by a white fungal growth.

Prevention & Treatment: Improve air circulation between plants and rows. Too much fertilizer favors heavy vine growth, creating areas for the disease to develop. There are no recommended chemical controls for the home garden.

Table 2. Fungicides to Control Bean & Southern Pea Diseases.

Fungicides Examples of Brands & Products
Chlorothalonil Bonide Fungonil Concentrate; & RTU1
Ferti-lome Broad Spectrum Landscape & Garden Fungicide Concentrate; & RTU1
GardenTech Daconil Fungicide Concentrate; & RTU1
Hi-Yield Vegetable, Flower, Fruit & Ornamental Fungicide
Ortho MAX Garden Disease Control Concentrate
Southern Ag Liquid Ornamental & Vegetable Fungicide
Tiger Brand Daconil
Copper Fungicides Bonide Liquid Copper Fungicide RTU1
Bonide Copper Fungicide Spray or Dust (wettable powder with copper sulfate)
Monterey Liqui-Cop Copper Fungicidal Garden Spray Concentrate (a copper ammonium complex)
Southern Ag Liquid Copper Fungicide (a copper ammonium complex)
Bonide Liquid Copper Concentrate (a copper soap)
Camelot Fungicide/ Bactericide Concentrate (a copper soap)
Concern Copper Soap Fungicide for Flowers, Fruit & Vegetables RTU1
Natural Guard Copper Soap Liquid Fungicide Concentrate; & RTU1
Sulfur Bonide Sulfur Plant Fungicide (dust or spray)
Ferti-lome Dusting Sulfur (also wettable for spray)
Hi-Yield Wettable Dusting Sulfur (dust or spray)
Safer Brand Garden Fungicide Concentrate
Southern Ag Wettable or Dusting Sulfur
1RTU = Ready-to-Use (a small pre-mixed spray bottle for use in small gardens)
To protect pollinating insects, always spray as late in the evening as possible.

Bean (Snap, Lima, and Butter Beans)

Phaseolus spp

Bacterial Blights: Halo Blight (bacterium – Pseudomonas syringae pv. phaseolicola); Common Blight (bacterium – Xanthomonas campestris pv. phaseoli): Plants infected with the halo blight bacterium form greenish-yellow circles around each lesion. Interior of the lesion turns brown. With age, lesions enlarge and coalesce. The entire leaf finally drops. Stem lesions appear as long, reddish colored spots. When the plant begins to set fruit, lesions are formed at the nodes which girdle the stem. This reduces fruit development. Common blight-infected pods do not exhibit the greenish-yellow halo around the lesion like halo blight lesions. Infected leaves with halo blight turn yellow and slowly die while those with common blight turn brown and drop quickly. Both organisms are seed-borne. Entry into the plant is through the leaf stomata. Rain and damp weather encourage development of these diseases. Common blight is more of a problem in warm weather while halo blight is favored by cool temperatures. Both bacteria can live in the soil for two years on plant residue. To control bacterial blight of beans, seed grown in the western United States should be planted. Avoid spreading the disease by not entering the field when the foliage is wet. Follow a three year rotation.

Anthracnose (fungus – Colletotrichum lindemuthianum): This is a seed-borne fungus which attacks all above ground portions of the plant. Infected seed are marked by dark, sunken lesions that extend through the seed coat. Stem lesions are oval and sunken. The center of the lesion is dark brown with purplish to red borders. In early stages, the fungus develops along the veins and becomes purplish to red in color. In advanced stages, leaves become ragged. Infection of the pods results in small, reddish, elongated spots. Older spots are sunken and have brown to reddish-brown borders. The disease is favored by cool, wet springs and falls. It disappears during hot, dry summers. The fungus can survive in the soil for two years in plant debris. Control is obtained by: (1) the use of disease-free seed, (2) crop rotation, (3) not entering fields when plants are wet, and (4) spraying with fungicides.

Cercospora Leaf Spot (fungi – Cercospora spp.): Lower foliage becomes marked by irregular tan spots one-eighth to one-fourth inch in diameter. Severe infection causes defoliation and plant stunting. It is reported to attack the pod but has only been observed on foliage in Texas. Infection is most severe during periods of extended rainfall, high humidity and temperatures between 75 to 85 degrees F. No resistance exists among varieties. Fungicide sprays should begin at first sign of disease and continued during cool, rainy conditions.

Root Rot (fungus – Rhizoctonia solani): Bean seed may rot in soil or the young seedling may become stunted. A reddish-brown canker is formed on the stem. Cankers may completely girdle the stem or may only partially girdle it, causing severe stunting. Beans should be planted after the soil has warmed to above 69 degreesF. Beans should follow a grass type crop.

Fusarium Root Rot (fungus – Fusarium solani f. sp. phaseoli): Plants infected with Fusarium are characterized by a reddish discoloration of the tap root. Affected plants are stunted with yellow leaves. Young rootlets formed in the area of the lesion are killed. If weather conditions are favorable, a normal crop may be produced. Avoid soils where Fusarium has been a problem. Long rotations (four to five years) will help reduce losses.

Pod Blight (fungus – Diaporthe phaseolorum): Pod blight of lima beans is first observed as brown pustules of irregular shape on the leaves. Lesions grow to one-fourth to three-fourths of an inch in diameter. During the latter part of the growing season, the fungus spreads to nearby pods, where it causes a pale watery spot. The spot enlarges and becomes darker with age. On pods the spot is marked by dark brown to black pustules on the surface arranged in a ring.

Use seed grown in the western United States and use a three- to four-year rotation. Follow a fungicide program to control the disease when it occurs consistently.

Mosaic (virus): Leaves become puckered and mottled with light and dark-green areas. Infected plants become stunted. The virus is seed-borne and can be spread by aphids. Losses can be reduced by growing resistant varieties and following an approved aphid control program.

Curly Top (virus): Infected plants are stunted and have distorted foliage. It is spread by the beet leafhopper. Use resistant varieties and practice good insect control.

Root Knot: (See Root Knot)

Southern Blight: (See Southern Blight)

Cotton Root Rot: (See Cotton Root Rot)

Sun Scald: In the early spring beans are often affected by a condition in which the young leaves turn light tan in color and die. This may happen to the entire leaf or to only a portion of the leaf. The conditions favoring disease development are cool to moderate temperatures, extended periods of high humidity, and cloudy days followed by a bright sunny day. Damage is usually restricted to only a few scattered leaves.

Rust (fungus – Uromyces phaseoli): Small reddish-brown pustules form on lower side of leaves. The fungus overwinters in crop residue. If rust has been severe, a rotation program should be practiced. Resistant varieties should be used when past experience indicates rust to be a problem. Apply approved fungicides at first sign of infection in the fall.

Powdery Mildew (fungus – Erysiphe polygoni): Powdery mildew is character- ized by a white powdery growth on the foliage. Infected pods and foliage become malformed. The fungal spores are spread by wind. Spray with approved fungicides. Powdery mildew seldom becomes an economic problem.

Watery Soft Rot (fungus – Sclerotinia sclerotiorum): The fungus affects the stems, leaves and pods of beans. First signs of infection are small, soft, watery spots that enlarge rapidly under cool, moist conditions. They may enlarge and coalesce and the stem is girdled. Infected pods turn into a soft, watery mass. Following the watery stage the affected tissues dry out and turn brown. Within a short time the brown areas are covered with a dense white fungal growth. With age, the white fungal growth turns gray and is dotted with small, hard black bodies called sclerotia. Most losses occur in shipping. Infected beans tend to stick together.

The disease is favored by temperatures ranging between 60 and 70 degrees F. Long periods of high humidity also favor the development of white mold. Large plants with heavy vine growth encourage disease development.

Sclerotia fall to the ground at maturity where they can lay dormant for as long as ten years. When weather conditions are again favorable, the sclerotia begin growth again. The fungus enters beans directly where pods and leaves come in contact with the developing fungus.

Sclerotia produce small mushroom-like structures which contain thousands of ascospores. The spores are ejected into the air landing on plant parts such as blossoms or decaying leaves and begin to develop. This may be repeated many times resulting in widespread infection.

Every effort should be made to improve air circulation between plants and rows. This can be done by increasing row spacing and decreasing the seeding rate. Excessive applications of nitrogen favor heavy vine growth and should be avoided. During periods of extended cool temperatures and high humidity, fungicides should be applied on a preventive schedule.

Baldhead: Beans emerge and produce cotyledons but nothing is formed above the cotyledonary leaves. This can result from injury from soil insects or fungi, and results from mechanically damaged seed.

GARDEN + GARDENING + GARDENING TIPS & ADVICE

Beans – Diseases, Pests and Problems

Basic Information

Problem: Cutworms
Affected Area: Stem
Description: Cuts off young plant just above the soil; no other damage apparent. Lives in soil around roots.
Control: If troubled, place cardboard collars around seedlings. Extend collar 1″ below soil and 1″ above the soil.

Problem: Mexican Bean Beetle
Affected Area: Leaf
Description: Yellow with black markings about 1/3 inch long with spines; said to resemble a pincushion. Eats the surface at the leaf blade leaving leaf veins. Larvae and egg clusters on underside of leaf
Control: Hand pick when small. Crush eggs. Clean up debris in the fall * Rotenone, Pyrethrum and Sevin are registered for use. Sevin can be used to day of harvest. Allow at least 1 day between Rotenone application and harvest. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.

Problem: Aphids
Affected Area: Leaf and Stem
Description: Small Insects found on new stems and the underside of the leaf. Usually green. They suck fluids from the plant leaving a honey dew substance behind. Leaves turn pale yellow.
Control: Insecticidal soaps, a strong stream of water, and most registered insecticides. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.

Problem: Mites
Affected Area: Leaf
Description: Small, about 1/50″ appear to be black, red, or green spots that move when placed on a white sheet of paper. Mites suck plant juices causing mottled, speckled, cupped, wilted, or dead leaves.
Control: Insecticidal soaps or a strong stream of water. Clean up debris in the fall. *Diazinon is registered but is ineffective. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.

Problem: Common mosaic
Affected Area: Leaf
Description: Yellow/green mottled leaves may cup downward and veins discolor and die. Plants are dwarfed and spindly.
Control: Use resistant varieties. Control aphids

Problem: Damping Off
Affected Area: Seedling
Description: Young seedlings wilt and die
Control: Use treated seed and let soil dry out between waterings.

Problem: Stem and root rot
Affected Area: Leaf, Stem, and Root
Description: Stunted plant with yellow leaves that drop. The main root discolors (red to black) and rots. Other roots die.
Control: Let soil dry between waterings. Cultivate deeply before planting. Rotate placement from year to year.

Problem: White Mold
Affected Area: Entire plant
Description: Water soaked spots on leaves or stem. White fungal growth on plant. Plants wilt and die.
Control: Cultivate deeply before planting. Rotate placement from year to year.

Problem: Alternaria Leaf and Pod Spot
Affected Area: Leaf, Stem, and Pod
Description: This disease is characterized by small flecks or tiny water-soaked spots that appear on infected green leaves and pods. Lesions that develop on leaves appear as circular to irregular spots and flecks with a pale brown center and a dark brown margin surrounded by a yellow halo. The lesions may develop concentric rings, and diseased tissue may become dry and brittle and fall out, leaving a shot hole in the leaf.
Control: Control of the disease on snap bean pods involves the use of wider plant and row spacing, fungicides, resistant cultivars, and crop rotation.

Problem: Angular Leaf Spot
Affected Area: Leaf and Stem
Description: This disease is characterized by lesions that develop on the leaf that are gray or brown irregular spots that may be bordered by a yellow halo. As the disease progresses, these lesions may group together, the plant becomes yellow, and drying leaves may fall off prematurely.
Control: The best form of control includes using pathogen-free seed that has been treated with an effective fungicide, rotating the crop where possible, and using resistant cultivars where available.

Problem: Anthracnose
Affected Area: Leaf and Stem
Description: This disease is characterized by small, dark brown to black lesions that usually appear on leaf petioles and on the lower surfaces of leaves and leaf veins. The lesions are elongate, angular, and brick red to purple, becoming dark brown to black. Infected seeds are often discolored and may contain dark brown to black cankers.
Control: The best form of control is to use resistant cultivars where available and to apply seed treatments, including benomyl and thiophanate methyl.

Problem: Ascochyta Leaf Spot
Affected Area: Leaf and Stem
Description: This disease is characterized by brown to black lesions that develop on the leaves. These lesions may have concentric zones that are 10-30 mm in diameter and contain small, black pycnidia. Dark gray to black lesions may also appear on the branches, stems, nodes, and pods causing the plant to become girdled and die. Infected seeds turn brown to black.
Control: The best forms of control include using fungicide sprays and rotating the beans with nonhost crops such as cereal or corn.

Problem: Ashy Stem Blight
Affected Area: Leaf and Stem
Description: This disease is characterized by wilting, yellowing, and death of the leaves that may only appear on one side of the plant. Lesions also develop on the seedling stem at the soil line during emergence and they are small, irregularly shaped, blackish, and sunken. Wilting, yellowing, and death of leaves may be more pronounced on one side of the plant.
Control: The best form of control is to use resistant cultivars where available, use pathogen-free seed, apply chemical treatment to the seed, and fumigate the soil.

Problem: Bacterial Brown Spot
Affected Area: Leaf and Pod
Description: This disease is characterized by lesions that develop on the leaves and are circular, brown, show areas of drying and are often surrounded by a bright yellow zone. Pods that become infected may be twisted or bent where the lesions develop.
Control: The best form of control includes using resistant cultivars and pathogen-free seed.

Problem: Bacterial Wilt
Affected Area: Leaf and Seed
Description: Soft, wilting leaves characterize this disease during warm, dry weather. Infected seeds may show purple or yellow discoloration and struggle to grow properly.
Control: If the disease is found, pathogen-free seed and control measures recommended for other bacterial diseases of bean should be used.

Problem: Bean Common Mosaic
Affected Area: Leaf, Tissue, and Growth
Description: This disease is characterized by light and dark green mosaic, leaf roll, malformation, yellow dots, and abnormally slow growth habits. The vascular tissues may dry out causing the plant to die if it is still young.
Control: The best form of control is the use of resistant cultivars.

Problem: Bean Golden Mosaic
Affected Area: Leaf
Description: This disease is characterized by fine, bright yellow lines that occur only in the veins of the leaves. The leaves curl and fail to expand properly and develop stiff and leathery surfaces. Leaves that may become completely yellow are usually distorted and may dry up.
Control: The best form of control is to use resistant cultivars and control whitefly vectors.

Problem: Bean Yellow Mosaic
Affected Area: Leaf and Growth
Description: This disease is characterized by either mild or diffuse yellow spotting with limited plant stunting, or coarse mosaic, rugosity, malformation, and severe stunting. Some cultivars may also develop dry spots, veinal and apical drying, wilting, and premature death.
Control: The best form of control is to use resistant cultivars.

Problem: Boron Deficiency
Affected Area: Entire Plant
Description: Boron deficiency is rare in beans, but may occur on coarse-textured soils with low organic matter content. Boron deficiency is characterized by crinkled, thickened, and leathery leaves. An early symptom is reduced growth or death of the apical meristem resulting in profuse lateral branches whose terminal buds die. Stems may be swollen near the nodes. Flowers and pods either do not form or they abort. The root system develops poorly.
Control: Boron deficiency is corrected by application of soluble boron salts. Beans are very sensitive to excess boron. Boron fertilizer rates are generally 0.5 lbs boron/acre or less. Because of potential toxicity, band applications are not recommended. Beans planted on soils with high boron may show toxicity symptoms which generally appear as firing of the leaf margins resembling salt injury.

Problem: Calcium Deficiency
Affected Area: Entire Plant
Description: Calcium deficiency is not commonly observed in beans. Most soils where beans are produced contain adequate calcium or are limed to raise soil pH. Deficiency symptoms include loss of turgor, death of growing points, and yellowing of young leaves. Pods may be soft and seeds may fail to develop. Calcium is a key component of cell walls and membranes.
Control: Deficiency is prevented by liming or application of soluble calcium salts such as gypsum.

Problem: Cercospora Leaf Spot
Affected Area: Leaf and Stem
Description: This disease is characterized by brown or rust colored lesions that develop on the leaves. These lesions may vary in shape from circular to angular and have a diameter of 2-10 mm depending on if the lesions group together. The lesions may also have a gray center with a slightly reddish border and severely affected leaves turn yellow.
Control: The best form of control is to use resistant cultivars.

Problem: Chaetoseptoria Leaf Spot
Affected Area: Leaf and Stem
Description: This disease is characterized by lesions that develop on the leaves that are irregular to circular, ash gray in color, medium to large in size and may have a diameter of approximately 10 mm with a reddish border and gray to black pycnidia in the center.
Control: The best form of control is to rotate the crop with nonhost crops for about 5 years.

Problem: Clover Yellow Vein
Affected Area: Leaf and Growth
Description: This disease is characterized by stunted plants that are malformed and have a yellow mosaic. Most plants also show apical drying, premature defoliate, and wilting that result in the death of the plant.
Control: The best form of control is the use of resistant cultivars.

Problem: Common Bacterial Blight
Affected Area: Leaf
Description: This disease is characterized by water-soaked spots that develop on the leaves. These spots gradually enlarge, becoming spongy and they dry out leaving a border of bright yellow tissue. Lesions can also be found at the margin and in areas between the veins of the leaf.
Control: The best forms of control include using resistant cultivars and spraying foliage with a copper-based bactericide.

Problem: Copper Deficiency/Toxicity
Affected Area: Entire Plant
Description: Copper deficiency, though rare, is most often observed in sandy, organic, or over-limed soils. Copper deficiency is characterized by stunted plants with shortened internodes and necrotic areas adjacent to the veins near the base of the leaflet. Leaves may show scorching, wilting, and senescence.
Control: Copper deficiency is prevented by application of soluble copper fertilizers, such as copper sulfate or copper EDTA. Fertilizer rates are generally about one lb Cu/acre. Rates of 2-3 lbs copper/acre may be effective for several years, but these rates should be broadcast not banded. Foliar sprays of copper sulfate or copper EDTA are also effective.

Problem: Cucumber Mosaic
Affected Area: Leaf and Pod
Description: This disease is characterized by curling, green or yellow spots, and blisters that develop on the leaves, and a dark green veinbanding, zipper-like appearance along the main veins. Plants that are flowering and become infected mostly show small, curved, spotted pods, but may also develop the other leaf symptoms in the apical leaves.
Control: The best form of control is to use virus-free seed and avoid planting in fields that may be infected or show signs of getting the disease.

Problem: Curly Top
Affected Area: Leaf and Bud
Description: This disease is characterized by a tight curl of the first trifoliate bud tips and yellowing of the trifoliolate leaf. As the disease progresses, the primary leaf also turns yellow and the plant dies.
Control: The best form of control is to use resistant cultivars.

Problem: Downy Mildew
Affected Area: Leaf and Stem
Description: This disease is characterized by lesions that develop on leaves and petioles and appear as white spots that enlarge and eventually cause the leaves to wilt and die. Major damage occurs as pods become infected and become covered by white, cottony patches of mycelium. Blossoms, buds, and other plant parts may also be killed if they are infected with the white mycelium.
Control: The best form of control is to use resistant cultivars, especially with lima beans, and applying a fungicide spray during flowering and pod formation.

Problem: Entyloma Leaf Smut
Affected Area: Leaf and Stem
Description: This disease is characterized by round or oval lesions that appear water-soaked and become gray-brown on the upper leaf surface and gray-blue on the lower leaf surface. Infected leaves exhibit a blister smut that appears as dark swellings on the upper leaf surface.
Control: The best form of control is to rotate the crop with non-host crops such as cereals and corn.

Problem: Floury Leaf Spot
Affected Area: Leaf and Stem
Description: This disease is characterized by light green to slightly yellow lesions that develop on the upper leaf surface. The lesions may be circular to angular and have a diameter of 10-15 mm. On the lower leaf surface, white, floury mats of conidiophores and conidia form and a heavy infection may cause defoliation.
Control: The best form of control is to apply chemical sprays such as benomyl and thiophanate methyl.

Problem: Fusarium Root Rot
Affected Area: Roots
Description: This disease is characterized by long, narrow, red to brown streaks that appear on hypocotyls and taproots of 7 to 10 day old seedlings. Plants that are established and become infected are usually stunted, vary in size and vigor creating an uneven top canopy, and depend on less important roots for survival.
Control: The best form of control is to practice good cultural control habits.

Problem: Fusarium Yellows
Affected Area: Leaf and Stem
Description: This disease is characterized by premature falling off of the lower leaves and yellowing of the leaves beginning just above the lowest leaves on the stem and progressing upward. As the disease progresses, the leaves become increasingly yellow until finally the plant is a bright yellow color. Plants become stunted if they become infected while they are still young.
Control: The best form of control is to use resistant cultivars where available.

Problem: Gray Leaf Spot
Affected Area: Leaf and Stem
Description: This disease is characterized by light green to yellow lesions that develop on the surface of the leaves. The lesions may be angular in shape, 2-5 mm in diameter on the upper leaf surface, and may group together and later become covered by the free, powdery, grayish white growth of the fungus.
Control: Resistant cultivars are the best form of control.

Problem: Grey Mold
Affected Area: Leaf and Stem
Description: This disease is characterized by lesions that are dark, water-soaked or translucent, soft and slimy and often develop zones of concentric rings. These lesions may girdle the stem or petiole in which case the distal parts of the plant are invaded and the plant collapses. As diseased tissues dry out, characteristic conidiophores and conidia are formed in a gray-brown, powdery mass, and sclerotia may be formed on bulky tissues, such as stems and pods.
Control: The best form of control is to use resistant cultivars.

Problem: Hail Injury
Affected Area: Entire Plant above ground
Description: Plants that suffer from hail injury usually have tattered leaves, broken or crushed stems and branches, and long, whitish, bruised areas on stems, branches, petioles, and leaves.
Control: NA

Problem: Halo Blight
Affected Area: Leaf, Stem, and Pod
Description: This disease is characterized by small, water-soaked spots that appear on the lower leaf surface and may develop a zone of yellow-green tissue around the point of infection. Stems and pods are also infected with pods developing red or brown, water-soaked lesions. If these lesions develop on mature, yellow pods, they may be green but exhibit crusty bacterial ooze on the surface.
Control: The best forms of control are to use resistant cultivars and apply bactericidal sprays containing fixed copper to reduce epiphytic populations and to control secondary disease spread.

Problem: Iron Chlorosis
Affected Area: Entire Plant
Description: Iron chlorosis, the name given to iron deficiency symptoms, occurs frequently in beans grown on high pH soils containing free calcium carbonate. Iron availability declines rapidly as soil pH increases. Water-logging of the soil worsens the symptoms, but the effect may be temporary and disappear as the soil dries. Iron chlorosis typically occurs on the new leaves as a distinctive yellowing of the tissue between veins while the veins remain green. Severely chlorotic leaves may be almost white and have necrotic areas.
Control: The best method of prevention is variety selection. So-called iron-efficient cultivars are less susceptible to chlorosis and should be planted if chlorosis has been observed previously and soil conditions are conducive to development of deficiency. Soil applications of iron fertilizers are generally ineffective in correcting iron deficiency. The most effective corrective treatment is foliar sprays of soluble iron materials, such as iron chelates or ferrous sulfate. A 0.5 to 1.0% solution of ferrous sulfate with a surfactant sprayed in enough water to wet the leaves (about 20 gals/acre) is effective. Multiple applications at 7-14 day intervals may be necessary.

Problem: Peanut Stunt
Affected Area: Leaf, Pod, and Growth
Description: This disease is characterized by mosaic, drying of plant tissues, rugged leaf edges, deformation, and stunting. Pods rarely develop and if they do they are small and malformed with only a few seeds being produced.
Control: There are no control measures available at this time for this disease.

Problem: Powdery Mildew
Affected Area: Leaf and Stem
Description: This disease is characterized by spots that are slightly darkened, about 10 mm in diameter, and develop on the upper surfaces of leaves. These areas become covered by a circular growth of white, superficial, powdery mycelium which may spread on the entire leaf and plant causing the plant to become distorted and yellow.
Control: The best form of control is the use of resistant cultivars.

Problem: Pythium Diseases
Affected Area: Roots
Description: This disease is characterized by plants that show a lesion, initially water-soaked but becoming dry, extending from the roots up the hypocotyl and sometimes reaching the growing point. This disease often affects seeds or seedlings which may become mushy and discolored, fail to emerge, or wilt and die within the first few weeks of growth.
Control: There are a few resistant varieties available and should be used. There are no other control measures for the disease.

Problem: Red Node
Affected Area: Leaf and Stem
Description: This disease is characterized by a reddening of nodes of the stem and a cushion-like swelling at the base of leaves and leaflets. These symptoms may also be accompanied by drying and reddening of veins of primary and trifoliolate leaves.
Control: There are no control measures available because of the minor importance of the disease.

Problem: Rhizoctonia Root Rot
Affected Area: Roots
Description: This disease is characterized by small, elongated, sunken, reddish brown lesions that appear on hypocotyls and roots in the early development of the disease. As these lesions grow and become more sunken, they become cankerous, and the red color may take over until the cankers are old. These cankers may girdle the hypocotyls if they group together which may result in preemergence or postemergence damping-off.
Control: The best form of control is to apply a heavy application of fungicides as a seed treatment of soil drench.

Problem: Rust
Affected Area: Leaf and Stem
Description: This disease is characterized by reddish brown, circular pustules on leaves or pods, which rupture the epidermis to produce abundant, powdery urediniospores.
Control: The best form of control is to use resistant cultivars where available. Not all cultivars are resistant to all forms of rust disease.

Problem: Southern Blight
Affected Area: Roots
Description: This disease is characterized by a slight yellowing of the lower leaves, water-soaking and slight darkening of the stem just below the soil line, followed by a yellowing of upper leaves and leaf drop. The fungus grows downward in the stem and roots, destroying the cortex.
Control: The best form of control is to use resistant cultivars.

Problem: Temperature Stress
Affected Area: Entire Plant
Description: Plants that are exposed to low temperatures may produce chilling or frost damage that appears as dark, water-soaked areas on wilted leaves or plants. If these low temperatures persist for an extended period of time, they may cause the plant to become stunted. High temperatures may cause flowers to abort, increase the rate of evapotranspiration causing leaf wilting or drying if there is an insufficient supply of soil moisture or if root growth is limited due to root rot, mechanical damage, or soil compaction.
Control: NA

Problem: Web Blight
Affected Area: Leaf and Stem
Description: This disease is characterized by small, dry spots on the leaves that are 5-10 mm in diameter with brown centers and olive green margins, originating from sclerotia. Infections caused by basidiospores appear as distinct, small, dry, circular lesions 2-3 mm in diameter that are light brown or brick red with a lighter center. Symptoms on pods are similar to those produced on foliage by sclerotia or basidiospores.
Control: The best forms of control are to apply chemical sprays with benomyl, carbendazim, and captafol and rotate with nonhost crops, such as cereals and corn.

Problem: White Leaf Spot
Affected Area: Leaf and Stem
Description: This disease is characterized by spots that develop on the lower leaf surface and appear as white, angular areas that are 2-5 mm in diameter and found only on the veins. These spots may become slightly gray with age and are pale green to yellow on the opposite, upper leaf surface.
Control: The best form of control is to apply benomyl sprays and use resistant cultivars where available.

Problem: White Mold
Affected Area: Leaf and Stem
Description: This disease is characterized by Infected flowers may develop a white, cottony appearance as mycelium grows on the surface. Lesions on pods, leaves, branches, and stems are initially small, circular, dark green, and water-soaked but rapidly increase in size, become slimy, and may eventually encompass and kill the entire organ.
Control: The best form of control is to use resistant cultivars where available, apply a fungicide spray, such as benomyl, during the flowering period, and rotate the crop with non-host crops, such as cereals and corn.

Problem: Zinc Deficiency
Affected Area: Entire Plant
Description: Beans are among the crops most sensitive to zinc deficiency. Symptoms are frequently observed in beans grown in high pH soils of low zinc content. Yield reductions and delayed maturity may occur without accompanying symptoms. Low soil organic matter, cold soil temperatures, high nitrogen and phosphorus levels, poor root growth, and compaction can all induce deficiencies. Deficient plants develop dwarfed or deformed leaves with a mottled interveinal chlorosis. Chlorosis progresses to necrosis as severity increases. Plants may be stunted with shortened internodes. Delayed maturity is a frequent result of zinc deficiency.
Control: Zinc deficiency can be prevented by soil application of water-soluble zinc sources such as zinc sulfate. Zinc EDTA is also effective, but costs significantly more. Insoluble zinc sources such as zinc oxide in granular form are ineffective. Band applications of 1-5 lbs Zn/acre are most effective. Banding of nitrogen and zinc together improves zinc uptake efficiency. Broadcast applications can also be used, but higher rates of 5-10 lbs Zn/acre are normally required for high pH soils. These rates may be effective for several years. Foliar application of soluble zinc fertilizers is also effective. A 0.5 to 1% zinc sulfate solution applied with a surfactant in enough water to wet foliage is an effective treatment. Repeated applications at 7-14 day intervals may be necessary.

Problem: Mites
Affected Area: Stem and Leaf
Description: Small, about 1/50″ appear to be black, red, or green spots that move when placed on a white sheet of paper. Mites suck plant juices causing mottled, speckled, cupped, wilted, or dead leaves.
Control: Insecticidal soaps or a strong stream of water. Clean up debris in the fall. *Diazinon is registered but is ineffective. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.

Problem: Common mosaic
Affected Area: Stem and Leaf
Description: Yellow/green mottled leaves may cup downward and veins discolor and die. Plants are dwarfed and spindly.
Control: Use resistant varieties. Control aphids

Problem: Damping Off
Affected Area: Seed
Description: Young seedlings wilt and die
Control: Use treated seed and let soil dry out between waterings.

Problem: Stem and root rot
Affected Area: Stem and Root
Description: Stunted plant with yellow leaves that drop. The main root discolors (red to black) and rots. Other roots die.
Control: Let soil dry between waterings. Cultivate deeply before planting. Rotate placement from year to year.

Problem: White Mold
Affected Area: Stem and Leaf
Description: Water soaked spots on leaves or stem. White fungal growth on plant. Plants wilt and die.
Control: Cultivate deeply before planting. Rotate placement from year to year.

Leave a Reply

Your email address will not be published. Required fields are marked *