Spots on green beans

My Beans Have Brown Spots

Bean Spots Have Multiple Causes

Insects, disease and age can all result in brown spots on beans, as can water problems (which may encourage disease). They include:

  • Anthracnose – fungus; severe damage near soil line.
  • Bacterial Brown Spot – water-soaked spots on foliage are brown with yellow margins.
  • Bacterial Blight – spots on both leaves and pods; rust-colored and may ooze yellow fluid.
  • Insects – aphids, various beetles and whiteflies cause chewing damage.

Brown Spots on Harvested Beans

With green beans (any bean harvested in the immature stage), the most likely reason for brown spots is that the beans are past their prime. They aren’t unsafe to eat, but you might want to use them in soups, stews or casseroles rather than as a stand-alone side dish. Store them in a plastic bag in the crisper drawer to keep fresh for about a week.

Brown Spots From Insects

Insects can cause brown spots in bean pods and bean leaves by feeding on them. In most cases, you’ll see a round hole that’s brown around the edges. Some insects may cause a brown blister-like lump on the bean pod. Although healthy plants can withstand a little insect damage, many insects either spread disease or allow organisms to enter through the holes they chew.

Brown Spots From Diseases

A number of diseases can cause brown areas on beans and bean leaves. Unlike insect damage, these are more likely to appear as irregular splotches, spots or streaks. Bacterial and fungal diseases are the most common culprits. The location of the discolored areas can be a clue to the cause, so inspect plants carefully. Color variations – yellowish, orange or purplish – can also provide clues.

Preventing Brown Spots

Prevention starts with identifying the problem. Check the soil to make sure it is neither too wet nor too dry. It should be moist about one inch below the surface. Look for insects – both flying and crawling – as well as egg clusters. Ensure your soil is fertile to give beans enough nutrition to withstand minor insect attacks. Remove and burn any plant that looks diseased.

Treating Bean Spots

Treatment, of course, depends on the cause. Fungal diseases often result from over-watering or sprinkling the leaves. Use drip irrigation and don’t work with wet plants. Fungal infections often respond to neem oil or tea tree oil, both of which have fungicidal properties. Spray plants every 10 days. Hand pick insects or use approved organic insecticides.

Beans Covered With Spots: Reasons For Brown Spots On Beans

Beans are one of the easiest crops in the veggie garden, making even the most beginning gardener feel like a massive success when their beans sprout an unexpected hoard of pods. Unfortunately, every year some beans covered with spots appear in the garden, especially when the weather has been wet. Brown spots on beans are commonly caused by bacterial or fungal diseases; but don’t worry, you may be able to save them.

Brown Spot Bean Plant Diseases

Brown spots on beans are common symptoms of bean disease, and many even occur under the same conditions, making it hard to know if fungal or bacterial disease is your problem. If you look closely though, you may be able to tell the bacterial bean spots from the fungal ones, simplifying treatment.

  • Anthracnose of beans causes large brown spots to appear on bean leaves, with damage most severe near the soil line. It may spread quickly, consuming the entire plant if left untreated. When anthracnose-infected beans are picked and brought inside, they quickly develop white fungal bodies on their surfaces.
  • Bacterial brown spot starts as small water-soaked spots on foliage, but soon expand into dead areas surrounded by a yellow margin. Sometimes these spots grow into one another or the dead material falls out of the leaf, giving it a tattered appearance. Spots on pods are brown and sunken, and young pods emerge twisted or bent.
  • Bacterial blight is a bacterial disease similar in appearance to bacterial brown spot, but water-soaked lesions will also appear on the bean pods. They soon enlarge into rust-colored areas, and under humid conditions may ooze a yellow fluid. Seed abortion or discoloration isn’t uncommon.
  • Halo blight can be distinguished from other bacterial blights by the red-orange leaf spots surrounded by green-yellow halos that range widely in size. Spots will almost entirely disappear when temperatures exceed 80 degrees Fahrenheit. These lesions may ooze cream-colored liquid when the weather is wet.

Treating Spots on Bean Plants

Beans covered with spots aren’t usually anything to panic about; they need immediate treatment, but with a quick response, you’ll be able to save most or all of your harvest. It’s helpful to determine whether the spots you’re seeing are caused by a fungus or bacteria so you can choose a chemical that targets that organism.

Treat fungal infections using neem oil, applied every 10 days for several weeks. Bacterial diseases are more likely to respond to a copper-based fungicide, but several treatments may be required to produce a suitable harvest. In the future, make sure to steer clear of the bean patch when foliage is wet to reduce the chances of spreading these diseases. Keep bean leaves and other shed material off of the ground, since these dead tissues can harbor pathogens.

red/brown spots on green beans

I wish I could tell you for sure about the bean rust, CityFarmer. There are toxic fungi but I’ve never heard anything about bean rust being one of them. Certainly, lots of fungus plants live with and on our veggies in every garden.
And, plants they are. It’s like growing another plant species out there – the fungus liked the conditions whether your veggies do or do not !
I’m trying to get a handle on how to deal with fungal diseases. Often, they are a real problem even if I’m skipping by without seeing many problems this year. (I’ll be out later this morning to clean the mildew damaged branches off the climbing rose :/.)
With the ornamentals, and snapdragons can be absolutely destroyed by rust, it is fairly simple to spray on some fungicide but I don’t want to spray just anything on my food crops. I’m willing to pull out the early plantings of summer squash if the mildew gets too bad for them and rely on later-planting of those younger and with more resistance, late in the season.
I can’t get bush beans to a healthy 2nd picking because of spider mites so I haven’t had to worry much about late season disease. Yes, I can kill the mites but it is also easy to have a 2nd planting of beans going in another bed somewhere.
With the fungal disease plants, conditions have been favorable so, maybe, making conditions unfavorable is why things like vinegar and bicarbonate solutions sometimes works against the diseases. Since, even my irrigation water is a high pH, I’m thinking about trying a vinegar solution to see how it works. BTW – I understand that it is potassium bicarbonate rather than sodium bicarbonate that is more effective against these diseases.
How milk solutions might fit into these methods, I don’t really know. I suppose, you’d get so many other organisms interested in the milk that the fungal disease might just be overwhelmed. Not to make light of the problem and Best of Luck with those beans, CityFarmer – but, cheese is real good on green beans. As a sauce, not as a spray . . .
Steve

Ministry of Agriculture, Food and Rural Affairs

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Black Pod Spot of Snap Beans

Table of Content

  1. Introduction
  2. Hosts
  3. Symptoms
  4. Disease
  5. Management

Introduction

The incidence of Black pod spot or Rusty pod fleck caused by the fungus Alternaria alternata has been increasing recently on snap beans. Infections can cause significant losses to fresh market snap bean growers. The superficial discoloration on snap beans grown for processing can be removed through the blanching process.

Hosts

The fungus is considered to be a weak parasite on many crops and has a wide host range including white beans and soybeans. It has been isolated from several common weeds including Lady’s thumb, Nightshade, Ragweed, and Barnyard grass. The fungus is a common soilborne fungus that helps break down organic matter.

Symptoms

Alternaria alternata infect leaves of snap beans causing small water-soaked flecks and frequenly go unnoticed. Symptoms are most obvious on the pods which appear as orange, rusty or brown coloured flecks just before harvest, usually in August and September (Figures 1 & 2). The pod flecks are caused when spores of the fungus germinate and infect individual plant cell, which sends out a signal to surrounding cells to die. With the surrounding cells dead, the fungus cannot advance and only a small fleck results. This defense mechanism is referred to as hypersensitivity. When plants with this type of resistance are showered with large numbers of spores, numerous superficial flecks may occur, reducing the quality of yield.

Figure 1. Symptoms of Black pod spot on a yellow snap bean variety.

Figure 2. Symptoms of Black pod spot on a green bean variety.

Disease

The fungus survives on plant debris in the soil and on weeds. Spores produced by the fungus can be wind-blown or rain-splashed from decaying plant debris onto snap bean leaves, flowers, and pods. Spores require about 4 hours of leaf wetness to infect. Severe disease is often associated with plants under stress either during cool and wet or hot and dry growing conditions. Isolated rain showers or dew periods experienced during cool August mornings are often enough to initiate severe disease. Although symptoms appear on mature pods at the end of the growing season, there is evidence that infections occur earlier on blooms, immature pods, and leaves. The fungus remains inactive after early infection until the plant begins to naturally senesce.

Management

There are considerable differences in susceptibility of snap bean varieties to Black pod spot. Most yellow snap bean varieties and some green varieties, such as Striker, Prosperity, and Eureka, appear to be very susceptible whereas varieties such as Stallion, Bronco, and Green Crop appear less susceptible. Growers may consider growing the less susceptible varieties in later plantings when the disease is most likely to occur.

Losses to this disease can be avoided by harvesting early, however, this also results in reduced yield. There are currently no fungicides registered for controlling this disease.

green bean plant disease

Hello again,

After more investigation there are a couple of possibilities for the black spots on your beans. The most often seen is black aphids that love the plant and produce copious amounts of honey due that promotes a dark growth of sooty mold ( black greasy stuff). The information below may help.

Good luck with your gardening.

Kathleen Z.

Caption: Bean aphid Photo by: K. Grey Bean : Bean aphids (revision date: 5/11/2015)
BiologyBean aphids are small, pear-shaped, dark green to black insects. These soft-bodied insects often feed in clusters on the shoot tips and leaves of new growth. Severe infestations can result in curled or deformed leaves and shoot tips. Aphid feeding can produce large amounts of honeydew, a sweet, sticky material that may attract ants or become covered with a dark growth of sooty mold. The summer form of the aphids may be found on various hosts including many vegetables, flowers, and ornamentals. The aphids typically overwinter on hosts such as euonymus and viburnum. Management Options
Non-Chemical Management

  • Encourage natural predators including ladybird beetles, lacewings, syrphid (hover) fly larvae, and parasitic wasps. Avoid use of broad-spectrum insecticides which kill beneficial insects.
  • Hand-wipe or prune to control small, localized infestations (when practical).
  • Wash aphids from plants with a strong stream of water.
  • Control honeydew-feeding ants, which may protect aphid colonies from predators.
  • Provide proper nutrition. High levels of nitrogen encourage aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer if necessary.

Select non-chemical management options as your first choice! Chemical Management
Apply when aphids first appear. Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

  • Concern Insect Killing Soap ConcActive ingredient: potassium laurate | EPA reg no: 50932-3
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc Active ingredient: azadirachtin | EPA reg no: 70051-6-42697
  • Safer Brand Insect Killing Soap Conc II Active ingredient: potassium laurate | EPA reg no: 42697-60
  • Surround At Home Crop ProtectantActive ingredient: kaolin clay | EPA reg no: 61842-18-56872
  • This list may not include all products registered for this use.

Images + Show larger images Caption: Bean aphid Photo by: K. Grey Pestsense | School IPM | IPM & Pesticide Safety | Acknowledgements | Hortsense Disclaimer WSU Urban IPM, 2606 W Pioneer, Puyallup WA 98371, (253) 445-4577, Contact Us
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Bacterial Brown Spot In Garden Beans

MANAGEMENT

Recommendations for managing bacterial brown spot typically include the integration of crop rotation and sanitation efforts to reduce inoculum levels, planting disease resistant varieties and pathogen-free seed, avoiding working in fields when plants are wet, and the use of copper-based bactericides to protect plants and reduce the spread of the bacterium. In areas and conditions where the bacterium is already present on plants, growing epiphytically, the focus should be on efforts that keep bacterial populations low and on minimizing conditions that favor disease development.

Sanitation efforts should include the prompt destruction of bean debris shortly after the final bean harvest. Plant material should be disked into the soil to promote rapid decomposition. Manage weed hosts and volunteer beans that can serve as sources of inoculum. Clean equipment and tools between use in infested and disease free fields, and clean harvesting machinery, seed-cleaning equipment, and storage containers at the end of the season. Rotate to non- host crops (corn, small grains, non-legume vegetables) for three to four years. Avoid the use of sprinkler irrigation if possible, or irrigate at a time (such as during dew formation) that will not increase the amount of time plants are wet. Do not reuse irrigation water.1,2,3

Resistance to bacterial brown spot is available in commercial bean cultivars. Studies have shown that Pss populations on resistant cultivars are lower than they are on susceptible cultivars grown under the same conditions. Lower populations (below the threshold that triggers the switch to pathogenicity) may be one reason why brown spot is less severe on resistant cultivars of beans.5,6

Disease management guides usually recommend the use of certified, pathogen-free seed, and in some cases, treatment of seed with streptomycin to eliminate any bacterial contamination on the outside of the seed. These methods reduce the likelihood that the bacterium will be introduced into a field. However, in areas where the bacterium is commonly present on crop and weed hosts, the importance of seedborne inoculum in the development of a disease epidemic is not clear because the bacterium can easily spread to bean plants as they emerge.1,2,3

During the season, growers should regularly inspect plants for symptoms of bacterial brown spot, especially after prolonged periods of high humidity and/or frequent rainfalls. Scout weekly from midseason to harvest. Begin treatments with bactericides at the first sign of disease.3

Copper-based bactericides can be used to slow the spread of the bacterium and reduce foliar populations. Example products registered for use on dry and snap beans include DuPontTM Kocide® DF Fungicide/Bactericide, Champ® Formula 2 Flowable Agricultural Fungicide/Bactericide, and Cuprofix® Ultra 40 Disperss® Dry Flowable Fungicide/ Bactericide.3,7 Apply the products according to label directions, typically at 7 to 14 day intervals, depending on weather conditions and label instructions. The bactericides are most effective if applied as protectant treatments early in the season during periods of cool to moderate temperatures and moist conditions. Bactericide applications to hail damaged plants shortly after the damage occurs can help protect wounded plants from infection.1 However, the overall effectiveness of bactericide treatments has been inconsistent, and bactericides are less effective during periods of persistently wet weather.3

Green beans

Greetings. Sorry for the delay on getting your question answered. Green beans can get a spot actually on the bean itself and the leaves. This can be caused by a fungus called Anthracnose. Anthracnose can spread from season to season so it is best to destroy plants and avoid planting green beans there for 2-3 years.

Another possibility is Bean Rust — Bean Rust is also a fungus and can result in our recent weather patterns. To control Rust you can apply a multi-purpose fungicide at the first sign of the disease. Weekly applications may be necessary. Follow the recommendation on the fungicide label.

It is important to make sure after each gardening season to clean up any debris and discard it from the garden. This can stop the spread of the disease cycle.

To determine exactly what fungus or disease your beans have please bring a sample of the plant to any extension office that is close to you. The Greenup County Extension Office is open from 8 am until 4:30 pm Monday- Friday and open during lunch. The telephone number for the office is 836-0201. Please let me know if I can assist you further.

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