Plants with yellow leaves

Secrets To Fixing Vegetable Plant Leaves Turning Yellow

Pests

Those pesky pests. The types of pests that are the causes of my plant leaf turning yellow are those with piercing-sucking mouthparts such as aphids, spider mites and whiteflies.

Aphids

Aphids

I get aphids pretty regularly and effectively kill them with insecticidal soap. This is a common recommendation. Something else you can do is plant flowers that attract beneficial insects such as ladybugs and hoverflies. They feed on aphids. This is my preferred method and I have resolved to try it next season.

Some plants that attract these beneficial insects are sweet alyssum, zinnias, nasturtiums (edible BTW), cosmos and zinnias. In fact, not killing off all the aphids means those new beneficial friends of yours will stick around-because you’re such a good host-giving them all that free food!!

Source: https://flic.kr/p/qa3KbK

Spider Mites

Spider mites are really, really small so it is very hard to detect them. Instead, you see the damage. Insecticidal soap works for killing them too.

Additionally, attracting those beneficial insects is well, beneficial.

Source: https://flic.kr/p/dt8PiQ

Safer Brand 5118 Insect Killing Soap – 16-Ounce Concentrate

Whiteflies

Spraying insecticidal soap is also effective in killing whiteflies.

Small warning on using insecticidal soap

Be careful in your enthusiasm to kill those little nuisances. Insecticidal soap can be mildly toxic to your plants. Some tidbits of advice.

  • Spray only every four to seven days
  • Dilute the spray even more than is recommended on the instructions (assuming you buy commercial insecticidal soap).
  • If you have hard tap water, use rainwater or distilled water instead. The chemicals typically found in hard water can actually damage your leaves.
  • If possible, buy a commercial soap (versus DIY) as they were specifically created to be sprayed on plants.

Having said that, I did make my own spray and it did kill the aphids. I believe I may have killed a few spinach and pepper leaves in the process but definitely not the whole plant.

Overwatering/Underwatering

I talk about this quite often. I was terrible at overwatering-until I bought my moisture meter. That whole thing about sticking your finger in to see if the soil felt moist enough just did not work for me.

I am sure this skill comes with many years of practice. My moisture meter has helped me keep my plants alive far longer! Nuff said.

Invest in yourself and buy a moisture meter. Best $10 you’ll ever spend!

Not Enough Sun

Yet another cause for the problem of why my plants leaves are turning yellow!

What’s Wrong With My Plant? (And How Do I Fix It?): A Visual Guide to Easy Diagnosis and Organic RemediesThis is a tough one too. Plants (especially vegetables) typically need an average of 6 hours of sun every day. Having said that, some plants like root vegetables can handle some shade. Additionally, you do not want to burn the plants. Not helpful either. If shade is a problem, can you move your plants to containers? Or can you trim your trees and shrubs to eek out as much sunlight as possible?

When we first moved to No Flo, before I planted anything, I spent days walking out to our yard during varying times trying to decide which part of the yard got the most sun (We are surrounded on all sides by pine, oak, piñon, etc. Gorgeous really-just gets in the way of growing my edibles.).

This actually turned out to be quite wise because the one part of our yard which seemed to be the most natural place to put the greenhouse was the worst for sunlight. The greenhouse needs to have a long side facing east without any obstruction. We had to do some serious thinking and maneuvering to make that happen but my plants are doing great in there.

Well, now you know how to solve the problem of vegetable plant leaves turning yellow. It is clearly not an easy answer but thankfully there are fixes and remedies for everything.

A small word of warning. Be very methodical about how you solve this problem. You want to research carefully (especially when trying to fix the soil nutrients) before throwing a bandaid on the wound. However, with diligence and patience you can get those leaves green again in no time!

Yellowing Veggie Leaves

Written by The Seed Collection Pty Ltd Date Posted: 30 March 2019

Every veggie gardener starts the growing season with visions of luscious green leaves and pristine produce for the table. Unfortunately, things don’t always work out that way.

By midsummer, you may find you’re faced with a vegetable patch full of straggly, yellowing foliage which looks anything but ready for the kitchen.

Does this mean your crop is a disaster? Not necessarily. There are several reasons for edible leaves to turn yellow, and not all of them rule out a tasty harvest.

Natural Growth

The most straightforward reason for yellowing foliage is the natural growth patterns of a plant. As it matures, its growing energies are directed toward the younger, more productive growth.

The older leaves start to die away, having done their job of raising the seedling to adulthood. This yellowing is perfectly normal, and will tend to affect all plants of the same variety at roughly the same time and rate.

But if the yellowing is affecting the whole plant, and some individuals are suffering more than others, it’s usually a sign of stress. There are several potential causes.

Watering Issues

It’s obvious that plants need water to grow. What’s perhaps less well known is that many plants react just as badly to over-watering as they do to drought.

Both too much and too little water can turn a plant’s leaves yellow, so it pays to kick the knee-jerk hosepipe habit, turn off the automatic sprinklers, and give your veggies just the right amount of moisture each variety needs.

Bad Weather

In a similar vein, your veggies could be suffering through poor weather conditions. They could be getting too little sunlight, or baking in an uncomfortable glare.

Likewise, they may dislike the average temperature of their home, or be sensitive to over-strong breezes.

There’s not a great deal you can do about your local climate, but you can position your veggies as best you can to give each one the conditions it prefers.

Nutrient Deficiencies

Several common nutrient deficiencies in your soil will turn leaves yellow, including low levels of nitrogen, iron, or potassium.

A reliable sign that nutrients are the issue is when leaves develop brown spots along their edges as well as yellowing or general loss of colour.

If you’re worried your soil is lacking vital nutrients, you can confirm your suspicions with a home testing kit. You can then rectify the deficiency with a suitable fertiliser, and work on organic soil improvement to prevent future problems.

Soil pH

Another soil problem could be its level of acidity or alkalinity. Generally, veggies prefer a fairly neutral soil pH, and again, a home soil-testing kit will give you a diagnosis.

Diseases and Pests

And lastly, plants that are under attack from pests or disease will often start to yellow as they weaken. Check for any visible signs of aphids, caterpillars, or other pests, as well as spots of mould or mildew.

Can You Eat Yellow Leaves?

Yellow leaves don’t necessarily need to be a disaster.

If disease is the cause, it’s best to dispose of infected plants carefully just for caution’s sake.

If pests are the problem, it’s likely you can still eat the leaves – if you really, really want to. A moth-eaten cabbage may well be perfectly safe to eat, but for most people, the compost heap or chicken coop is the more attractive location.

However, for all other causes, there’s no reason you can’t still enjoy leaves that aren’t the perfect colour. They may taste a little different to the greener leaves, but that’s not necessarily a bad thing.

For example, some particularly bitter salad leaves are intentionally ‘forced’ as they grow, depriving them of sunlight to turn them yellow and sweeten their flavor. While your own yellow leaves may be unintentional, it’s worth a nibble to see if the accident is a happy one.

And if the effect on taste or texture isn’t entirely positive, you may be able to compensate in the kitchen. Maybe the leaves could be used in a stir-fry dish rather than a salad. Maybe you could push them in the direction of a pickle or fermentation jar, where strong and unusual flavors are more welcome.

But whichever way you use them, yellow leaves are still packed with nutrition. They’re probably much healthier than typical mass-produced supermarket fodder, grown for speed and economy and then stored for days or weeks before reaching the shelves.

However, there’s a limit to how far you should go in eating yellow leaves. Follow your senses and throw anything that’s unappetising onto the compost heap. Better still, try and solve the problems which stressed your veggies in the first place, so that next year your yellow leaves will all be deliberate.

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Plant leaves can tell many things about the health of your plants. Most of the times, the color of the leaves indicates whether a plant is healthy or not.

Naturally, the leaves of most plants are green because they contain a green-colored pigment called chlorophyll.

When the plant leaves turn to another color, fully or partially, this is a sign that something is wrong and the plant is not happy.

Yellowing of plant leaves that are normally green is known as chlorosis.

In today’s post, I will address the most common causes of why the plant leaves turn yellow and how you should approach each situation.

Some of these conditions might only occur to potted plants, while others can apply to both potted and to the garden plants.

Disclosure: This page contains affiliate links. This means that the owner of this website might be compensated for any qualifying purchases made via these links.

1. Over-watering or poor drainage

Ryan Dickey ,via Wikimedia Commons

Over-watering is one of the most causes of why many plants suffer.

When people start a garden or grow a plant for the first time, they want to make sure they give the plants enough water, without realizing that different plants have different moisture requirements.

Several examples of common plants that don’t need too much water are tomatoes, beans, and spinach.

Over-watering tomato plants is probably one of the most common mistakes. Even though tomatoes like to grow in humid soil, too much water can harm the plants and their fruits.

Too much humidity in the soil can lead to plant suffocation, root rot, and favors the appearance of various fungus diseases.

When you make your plant watering schedule, you should also take into account a few factors like the soil type, time of the year, climate, etc.

A very handy tool to determine when you need to water your plants is a soil moisture meter, which you simply insert into the ground and tells you the exact level of humidity in the soil.

Buy it on Amazon

Poor water drainage can harm your potted plants just like over-watering, therefore, make sure that the containers allow the excess water to drain out.

Common visible signs of plant over-watering are curled leaves, yellow leaves, cracked fruits, and lumps on the lower leaves.

2. Not enough nutrients in the soil

Peaceray ,via Wikimedia Commons

Just as the human body needs vitamins and minerals in order to stay healthy, plants also require various nutrients for vigorous growth.

A common cause why the leaves of your plants might turn yellow is the lack of the essential nutrients in the soil.

If you cultivate your plants in the same soil every year, without adding any type of fertilizer or compost, eventually, the land will become an inadequate environment for healthy plant growth due to the lack of enough nutrients.

Different plants have usually different needs in terms of the nutrients they require.

Three of the essential elements that plants need are nitrogen, phosphorus, and potassium. Other important nutrients for plant growth are calcium, magnesium, and sulfur.

Depending on the type of plants, you can use a specific type of fertilizer or a continuous-release all-purpose fertilizer which can feed up your plants for several months.

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Besides adding fertilizer, crop rotation is also recommended in order to prevent pests, plant diseases, and to maintain better soil fertility over time.

3. Too much fertilizer

Fertilizer for geraniums

A soil that doesn’t have enough nutrients is not good for your plants’ growth. Yet, if you use too much fertilizer, your plants will also not be happy.

Adding too many nutrients to the soil can make it hard for plants to absorb other nutrients and the needed amount of water. Also, applying an excessive amount of fertilizer can change the pH of your soil, which is the measure of the acidity and alkalinity in the soil.

How do I know when plants need fertilizer?

Probably, the best way to determines what nutrients your soil needs is to perform a soil test. Fortunately, you can easily do that using a soil test kit.

Buy it on Amazon

A soil test will enable you to determine what type of fertilizer is best for your soil type and how often you should apply fertilizer.

Below are several common signs of over fertilization.

  • The lower plant leaves turn yellow or dry out
  • Margins of the leaves turn brown
  • Leaves dry out and fall down

4. Dehydration

The human body is made up of about 60% water and severe dehydration can kill us.

Regarding this aspect, we are very alike with plants. The only difference is that a plant can be made up to 95% water.

Dehydration is a common cause of why the plant leaves turn yellow.

There isn’t a general rule about how often you should water your plants since there are many factors that impact this decision.

First of all, different plants need different humidity levels in the soil.

For instance, succulents are more adapted to arid environments and you shouldn’t water these plants as often as you water the cucumbers in your garden.

The soil type is another factor that you should consider when you determine how often you should water your plants.

The most common three types of soils are sand, clay, and silt.

Some soils retain water for a larger amount of time, while others dry up much faster.

Between these three soil types, silt is considered to be the best concerning the proper balance between water retention and drainage.

Clay usually retains a very large amount of water, but it is very poor at water drainage. This can lead to numerous fungal infections and the rot of the root of the plants.

Sandy soil is not good to retain water and it’s also not rich in nutrients.

Climate, time of the year, temperature, are several other factors that you should take into account when it comes to making your plant watering schedule.

Keep in mind that, as stated before, over-watering will also harm your plants. However, dehydration will kill the plants faster in most of the cases.

5. Not enough sunlight or too much

Sunlight is a required ingredient for the healthy growth of a plant.

Most plants need sunlight in order to achieve photosynthesis.

Photosynthesis is the name of the process by which the green plants use the sunlight to convert carbon dioxide and water into sugar molecules and oxygen.

The glucose resulted throughout this process will then be stored and used as a fuel for the plant.

If a plant doesn’t receive enough sunlight, its leaves will usually have a yellowish color. Sometimes, the plant will grow taller than usual but due to the lack of sunlight, it will not be very productive.

Keep in mind that sudden exposure to direct sunlight can also harm the plants and cause what it’s known as sunscald.

A good example would be of the seedlings that grew in a place with not so much direct sunlight and which are transplanted in a greenhouse.

I recently learned this lesson the hard way after my tomato plants seedlings were affected by sunscald after I transplanted them in a greenhouse. You can read the full post here.

Too much sunlight can also create problems to some plants.

Some plant types like to grow in shade or partial-shade (lettuce, broccoli, Brussel sprouts, geraniums, radishes, kale, etc.) and prolonged exposure to direct sunlight can cause them difficulties.

6. Fungus or virus infection

Plant leaves can also turn yellow when the plant has been affected by a fungus infection or a virus.

According to an article posted by Jim Isleib for Michigan State University, about 85% of the plant diseases are caused by fungal or fungal-like organisms.

In many cases, the plant contacts the fungus when its leaves come in contact with the soil or when the bottom leaves are splashed with tiny drops of dirt.

Most fungi develop in warm and moist environments.

When a plant is affected by a fungal infection, usually, you can see the first signs on its leaves, but this rule doesn’t always apply.

Not all the time the leaves of the plants affected by fungus turn yellow or entirely yellow. Sometimes the disease starts with brown spots on the lower leaves like in the case of the tomato early blight, or septoria leaf spot.

Plants can also be affected by viruses.

For example, the rose mosaic virus creates yellow patterns on the leaves of the roses. Sometimes, these color patterns look like a mosaic, therefore, the name “mosaic virus.”

Rose Mosaic Virus

7. Pest problems

By OliBac from FRANCE ,via Wikimedia Commons

Another reason why the leaves of some plants could turn yellow is a pest problem.

Some of the most widespread garden pests that cause this problem are Aphids.

Aphids (also known as greenfly or blackfly) are small insects who feed with plants’ sap.

These tiny insects are some of the most common garden pests. Despite their size, aphids can cause significant damage to a plant.

Aphids live in colonies and once they find a plant to feed with, they usually come in a large number.

Some species of aphids inject a toxin into plants which can cause leaves to curl, distort, or turn yellow. They also can transmit viruses from one plant to another.

Not only the trees and plants in your garden can be the target of aphids. These pests can also spread to indoor plants.

If your plants have aphids, you should spray them with Neem oil.

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Neem oil is a natural insecticide and fungicide that can help you get rid of several common garden pests and fungi like powdery mildew, spider mites, black spot, aphids, whitefly, and more.

8. Compacted soil / Crowded roots

Robert-Owen-Wahl

Plants need a mixture of oxygen and water in the soil for healthy growth.

A common mistake that many people do when transplanting a plant is to press the soil around the roots too strong.

If the soil is too compacted and not enough oxygen reaches the roots of the plant, therefore, its leaves turn yellowish and the plant slowly dies.

The soil becomes even more compacted every time the plant is watered.

This problem is especially common for potted plants. In nature, earthworms loosen and aerate the soil through the tunnels they dig into the ground.

A similar problem of the potted plants is that these sometimes don’t have enough room to grow and their roots become too crowded and compacted.

9. Plant aging

Bernskbarn ,via Wikimedia Commons

The yellowing of plant leaves is not always caused by a disease, nutrient imbalance or the lack of sunlight. Sometimes, the leaves turn yellow just because the plant has reached its full maturity.

Just as humans grow old, plants do age as well. The aging process in plants is known as senescence.

Many plants, especially the ones we grow in our gardens are seasonal plants, which means they will only last for one season.

There are also many perennial plants and trees with a long lifespan. For instance, the oldest recorded living tree in the US is believed to be over 5000 years old.

Some houseplants can also thrive for many years if they have the proper conditions.

Conclusion

There are numerous reasons why the plant leaves are turning yellow. Some can be related to a disease, pests, improper humidity, transplanting stress, not enough or too much sunlight, plant aging, etc.

In general, when some of the leaves or all the leaves turn suddenly yellow, that’s a sign that something disturbs the plant. Since the reasons depend upon so many factors, it’s up to you to determine the exact cause based on the information presented in this article.

Summer Leaf Yellowing and Drop on Trees

Another reason for leaf drop is disease, and the same ‘wet spring followed by hot summer’ scenario is also a perfect set-up for leaf diseases. In this case the leaves will have significant spots or brown areas.
It’s important to rake up affected leaves and dispose of them to reduce the chance of spreading disease in following years, but again, unless the tree is defoliated repeatedly, it’s not too much of a concern. And just as trees have varying reactions to hot and dry conditions, some trees are more susceptible to disease.
(While technically you could spray diseased trees, that is better done 1) before the disease takes hold, particularly on frequently affected trees and 2) on smaller trees, as spraying large trees is often not practical from a cost/benefit standpoint.)
You can (and should) water your trees in dry periods to reduce stress, but don’t fertilize until fall-trees know how to deal with the conditions and you don’t want to encourage leaves that can’t be supported.

When should you be concerned with early leaf drop? If twigs and branches are dying you may have a more serious problem. You can tell dead twigs from live twigs because they are brittle and snap when bent, as opposed to live twigs which should still be plump, be supple and bendable. You should also be concerned if your tree defoliated heavily (over 50% leaf loss) for two years in a row, or if there is evidence of insect infestation causing drop.

Blackberries Part 2-Diseases

  • By Cleve Campbell
  • /
  • June 2017 – Vol. 3 No.6
  • /

In the April 2017 issue we talked about starting a blackberry patch: environmental requirements, selecting varieties, planting and harvesting. This month we will continue our discussion on potential diseases that may invade your blackberry patch. There are a number of diseases that can attack blackberries. Knowing what to look for is the first step in controlling problems that may arise in the blackberry patch.

Blackberry Diseases:

Anthracnose is the result of a fungus that attacks the leaves and canes of the plant. You may first notice spots on leaves and/or canes. In late spring, the spots on the leaves are small with gray centers and purple margins. Leaf infection rarely causes defoliation, but the spots enlarge and become oval in shape and sunken. The infected tissue may eventually drop out and give the leaf a shot-hole appearance. On the canes, anthracnose symptoms first appear as small purplish spots on young canes (primocanes) and spurs. The spots enlarge and develop rather conspicuous borders (dark in color) with gray centers. In general, fruit on infected canes ripens abnormally. Infected canes may become girdled or cracked, causing either decline or death. If the planting is seriously infected, anthracnose is best controlled by removing and destroying all canes during the spring pruning.

Blackberry cane lesions caused by the fungal disease Anthracnose. Photo Credit: Phillip M. Brannen, Plant Pathology Department, University of Georgia.

Cane Blight – This disease is caused by the fungus, Leptosphaeria coniothyrium, which sporadically attacks canes of all Rubus species. Cane blight usually affects only canes that have been wounded in their vegetative year. All symptoms of cane blight occur in close association with wounds. Infection occurs in late spring or early summer through pruning — especially large pruning cuts — and insect wounds. In the spring, buds fail to break dormancy, lateral shoots wilt, or fruiting canes die when the fruit begins to ripen. Canes are usually brittle at the point of infection, and may break if bent. Symptoms appear late in the season on new shoots where plants have been pruned. Infected areas are brownish purple and develop from the cut ends. Branches originating in the infected areas wilt and die. Fruiting canes show a sudden wilting of branches when the fruit begins to ripen. Weakened canes are more susceptible to winter injury.

Symptoms of cane blight. Following infection, dead and dying floricanes are observed in the spring and summer. Dead canes may have a silvery to gray appearance.

Blackberry Cane blight. Photo Credit: Department of Horticulture Science, N.C. State University

Septoria Leafspot is caused by a fungus – Mycosphaerella rubi. The symptoms are similar to anthracnose leafspots. Spots tend to remain small with light brown or tan centers. Tiny black specks visible with a hand lens develop in the centers of leafspots. Chemical control is not usually necessary.

Septoria Leafspot on Blackberry Leaf. Photo Credit: Paul Bachi, University of Kentucky and Education Center, Bugworld.org

Rosette (fungus – Cercosporella rubi): This disease is also called double blossom or “witches’ broom.” Symptoms appear in the spring as bunches or clusters of foliage at terminals or along fruiting canes. Flower buds are larger and redder than normal. Petals may be purplish, and sepals are much elongated. Infected flowers do not set fruit. Control rosette by removing infected canes as soon as they become noticeable. Destroy all wild berry plants in the vicinity. Remove and burn all fruiting canes soon after harvest and keep plants adequately spaced for good air circulation. Where heavy infection has occurred, mowing all canes to the ground may be necessary.

Blackberry Rosette Disease. Photo Credit: Department of Horticulture Science, N.C. State University

Verticillium wilt causes the leaves to turn yellow, starting at the bottom of the canes and progressing upward. Infected canes are stunted and eventually wither and die.

Verticillium wilt. Photo Credits: Bernadine C Strike, University of California & Natural Resources.

Phytophthora Root Rot The fungi that cause Phytophthora root rot live in the soil and occur under wet and poorly-drained soil conditions. Blackberry plants that have wet feet are often predisposed to Phytophthora root rot. Excess water not only promotes susceptibility of roots to this disease, but also aids the fungus in moving to new infection sites.

Symptoms

Disease symptoms may first become noticeable in the spring, initially occurring in areas of the planting that are low or poorly drained. Foliar symptoms can include marginal browning, red or purple coloration, and/or chlorosis. Off-color leaves may also be smaller than normal. Infected plants show low vigor, developing fewer canes than usual; the canes that are produced may be weak and stunted. Stressed plants become more susceptible to other diseases, as well as to winter injury. Severely infected plants collapse and die. None of these symptoms alone are definitive for Phytophthora root rot since other factors, such as prolonged flooding or canker diseases, can result in similar symptoms. Diagnosis requires a careful examination of the main roots and crown of dying (not yet dead) plants. The tissue beneath the root epidermis or bark is white on healthy roots, while a typical reddish-brown discoloration is evident with Phytophthora-infected roots. Often a clear line of demarcation can be observed between diseased and healthy portions of the root. A laboratory test is often required to confirm the presence of Phytophthora.

Did you know that the Extension Office can send a sample from your infected plant to the plant pathologists at Virginia Tech, who will then send you a report with their diagnosis? If you’re interested in this, contact the Help Desk first to find out how to prepare your sample. You can call (434) 872-4580 or email: [email protected] The Extension Office is located at the Albemarle County Office Building on 5th Street Extended, 2nd floor. Find out more at piedmontmastergardeners.org/contact.

Photo Credit:Phillip M. Brannen Plant Pathology Department University of Georgia

Orange rust is also a concern on blackberries. In the spring, the undersides of the leaves are covered with bright orange fungal growth. Unlike all other fungi that infect blackberries, the orange rust fungus grows “systemically” throughout the roots, crown and shoots of an infected plant, and is perennial inside the below-ground plant parts. Once a plant is infected by orange rust, it is infected for life. Orange rust does not normally kill plants, but causes them to be so stunted and weakened that they produce little or no fruit. Key control methods are cultural practices such as removing infected plants early in the spring and eradication of any wild blackberry plants growing near the planting.

Symptoms
Orange rust-infected plants can be easily identified shortly after new growth appears in the spring. Newly formed shoots are weak and spindly. The new leaves on such canes are stunted or misshapen and are pale green to yellowish. This is important to remember when one considers control, because infected plants can be easily identified and removed at this stage. Within a few weeks, the lower surface of infected leaves are covered with blister-like pustules that are waxy at first but soon turn powdery and bright orange. This bright orange, rusty appearance is what gives the disease its name. Rusted leaves wither and drop in late spring or early summer. Later in the season, the tips of infected young canes appear to have outgrown the fungus and may appear normal. But appearances can be deceptive! At this point, infected plants are often difficult to identify. In reality, since the plants are systemically infected, the infected canes will be bushy and spindly in future years, and will bear little or no fruit.

Orange rust on Blackberry leaf. Photo Source: N.C. State University

Crown Gall (Agrobacterium tumefaciens): Wartlike growths (galls) appear on the roots or crowns of infected plants. Galls may range in size from that of a pinhead to several inches in diameter. Plants are weakened and yield dry, poorly developed berries. Galls are caused by bacteria present either in the soil or on planting stock. The bacteria enter the plant only through wounds or growth cracks.

An example of crown gall. Photo Credit: N.C.State University

The key to controlling diseases in your blackberry patch is sanitation. The following suggestions will improve your chances of a healthy blackberry patch and improve your chances of producing a more bountiful harvest.

  • Avoid “wet feet” by selecting a well-drained location. Consider a raised bed to reduce the likelihood of root diseases.
  • Select disease-resistant varieties.
  • Only disease-free plants should be planted. Before planting, inspect all plants and cut off and burn any old or diseased stems.
  • Remove as many wild blackberries growing nearby as possible. The folks at the Tennessee Agricultural Extension Service recommend a minimum distance of 300 feet.
  • If cane diseases become a problem, cut all plants at the soil line and destroy. For varieties with a double blossom, cut canes back to 12 inches above the ground immediately after harvest.
  • Remove all old canes soon after harvest.
  • Keep the blackberry patch free of weeds. Weed removal allows good air circulation, which helps reduce conditions favorable for disease development.

Blackberries are a wonderful garden addition. With a little care, a properly established blackberry patch will provide you with years of fresh gourmet and healthy treats.

Thanks for joining us in The Garden Shed. We look forward to your visit next month.

SOURCES:

“Small Fruit in the Home Garden,” https://www.pubs.ext.vt.edu/426/426-840/426-840.html

“Field Identification and Management Strategies of Common Diseases in Blackberry Production,” https://extension.missouri.edu/greene/documents/Horticulture/Blackberry/BlackBerryDisease16.pdf

“Cane Blight of Blackberry,” http://extension.uga.edu/publications/detail.cfm?number=C894

“Blackberries,” https://galveston.agrilife.org/files/2012/03/Fruit-Nut-Production-Blackberries.pdf

“Management of Important Blackberry Diseases in Arkansas,” https://www.uaex.edu/publications/PDF/FSA-7563.pdf

“Rosette (Double Blossom) of Blackberry,” https://www.ars.usda.gov/ARSUserFiles/5276/BlackberryRosetteInformation.pdf

“Cane Diseases of Brambles,” http://plantclinic.cornell.edu/factsheets/canediseasesbrambles.pdf

“Diseases of Small Fruits,” https://ag.tennessee.edu/EPP/Redbook/Small fruit diseases.pdf

“Blackberries and Raspberries in Home Gardens,” https://extension.tennessee.edu/publications/Documents/SP284-C.pdf

Blackberry, Dewberry, and Boysenberry

Algal Spot (alga, Cephaleuros sp.): Light green to light orange spots develop on canes. Spots can merge to cover entire portions of canes. This disease has not been studied in detail, especially relating to overall damage. Copper type fungicides are recommended for control. (See Photo of Algal Spot)

Anthracnose (fungus – Elsinoe veneta): A common cane and foliage disease of blackberry and dewberry sometimes called dieback. The disease first appears in the spring as small purplish spots on new shoots and purple bordered spots on leaves. Spots on canes enlarge, usually develop an oval shape, and gradually turn gray. Ends of badly infected canes die back. Erect types are less susceptible than the more spreading types. Late dormant fungicide application will help prevent infection. (See Photo of Anthracnose)

Cane and Leaf Rust (fungus – Kuehneola uredinis): Small, lemon-yellow pustules develop on canes and leaves throughout summer. Cracking and drying of canes and spotting and drying of leaves result. The disease is not systemic and does not affect blooming. Prune out and burn infected canes. It is a minor fungal disease. (See Photo of Cane and Leaf Rust)

Fruit rots (fungi – Botrytis sp., Penicillium sp.): Mild, wet weather conditions are ideal for fruit rot fungi. Overripe fruit is most susceptible. Timely harvest and spacing plants for good air circulation help prevent fruit rots. Fungicides are available but should not be overused due to resistance development in the fungal populations.

Cane Gall, Crown Gall, and Hairy Root (bacteria – Agrobacterium rubi, Agrobacterium tumefaciens, Agrobacterium rhizogenes): Cane galls are large, bark splitting swellings in long masses. Crown gall consists of large warty galls on roots or at base of canes. Where hairy root is involved, small wiry roots grow singly or in bunches from the main root or base of stem. Remove and destroy affected plants. Avoid replanting where diseased plants were removed. Examine nursery stock for evidence of galls and hairy root. Do not plant stock with galls or plants that have had galls removed.

Nematodes Other Than Root Knot (Xiphinema spp and others): Xiphinema or dagger nematode damage results in root swelling especially at the tips. Symptoms can be confused with root knot nematode damage as seen on other crops. Dwarfed fruiting canes and smaller fruit result. Damage is more severe on light sandy soil. Severe nematode damage can be avoided by planting clean root cuttings in soil where only grasses or small grains have been allowed to grow for three to four years. Commercial producers in problem areas may need to consider a pre-plant fumigant. Root knot nematode is not a problem on caneberries. See Section on Nematodes. (See Photo of Nematodes)

Orange Rust (fungus – Gymnoconia peckiana or Kunkelia nitens): Symptoms first appear as small, yellow spots on both sides of leaves. These spots enlarge on the underside to form irregular shaped pustules that rupture to release masses of orange spores. The fungus becomes systemic in plants, and affected plants never recover. No fruit is produced. Diseased plants, including all roots, should be removed and burned when first noticed and before pustules break open. Control weed growth and remove fruiting canes after harvest to improve air circulation. Destroy wild brambles and dewberries in adjacent areas. Fungicides are not effective against this rust. Varieties vary in their susceptibility to this fungus. Most thorn type blackberries are resistant. (See Photo of Orange Rust)

Rosette (fungus – Cercosporella rubi): This disease is also called double blossom or witches’ broom. Symptoms appear in the spring as bunches or clusters of foliage at terminals or along fruiting canes. Flower buds are larger and redder than normal. Petals may be purplish, and sepals are much elongated. Infected flowers do not set fruit. Control rosette by removing infected canes as soon as they become noticeable. Destroy all wild berry plants in the vicinity. Remove and burn all fruiting canes soon after harvest and keep plants adequately spaced for good air circulation. Where heavy infection has occurred, mowing all canes to the ground may be necessary. The new thornless blackberry varieties, Navaho and A. (See Photo 1 and Photo 2 of Rosette)

Septoria Leafspot (fungus – Mycosphaerella rubi): A fungus disease causing symptoms similar to anthracnose leafspots. Spots tend to remain small with light brown or tan centers. Tiny black specks visible with a hand lens develop in centers of leafspots. Chemical control is not usually necessary.

Virus Diseases: Viruses transmission has not been determined. Diagnosis of specific viruses is difficult based on symptoms. Viral symptoms include mosaic on foliage, stunting, leaf curl, leaf distortion and sterility or partial sterility. Poorly developed fruit, known as nubbins, may occur with normal fruit in the same cluster. See section on Virus Diseases.

Fungicides used to treat Blackberry, Dewberry, and Boysenberry Diseases
Anthracnose Septoria Leafspot Fruit Rots
Copper Hydroxide Copper Hydroxide Benomyl
Copper Sulfate Copper Sulfate Iprodione

The Clemson Extension office receives all types of calls about problems in the garden. One of the most common questions is: “Why are my leaves turning yellow?” The question may refer to plant, tree or vegetable leaves and the answer may be different for each type of plant. Let’s look at a few of the possibilities with the understanding that there could be more reasons than we can cover in our allowed space.

House plants: Too much water is the problem in the majority of cases when a plant’s health is declining. Several factors determine the appropriate frequency of watering: type of plant, temperature/humidity, pot size, light and drainage. Checking the plant on a regular basis instead of adhering to a strict schedule is better than overwatering, which drowns the roots. Some plants are heavier feeders than others and will need to be fed more often. Using a weakened solution of a soluble fertilizer when watering your plants is better than a strong dose every once in a while. Aphids, scale insects, mites and root damage due to fungal infections can cause yellowing of the leaves on houseplants. Mite infestation is facilitated by warm, dry environmental conditions. While most plants respond well to bright light, individual plants have different needs both for the amount and the intensity of the light they require to grow and thrive. Yellow leaves can indicate that your plant is either receiving too much or too little light. Investigate the proper light requirements for your specific plant. Yellow leaves, especially if they are on the lower portions of the plant, can be an indication that the roots are overgrown in the pot. Rubber plants are particularly prone to this problem. Some loss of foliage is normal. The length of time the leaves remain on the plant depends on the species.

Outdoor plants: There are many reasons why an outdoor plant’s leaves may turn yellow and possibly die. Sometimes this yellowing process is perfectly natural, and other times it is caused by environmental changes or pests. Every year in the fall, deciduous perennial plant species enter a state of dormancy, where they shut down their metabolism for the winter. As winter nears, plants and trees absorb the nutrients in their leaves, then shed the leaves to the ground below. With the coming of spring, deciduous plant come out of dormancy and grow new leaves for the coming year. Leaves may turn yellow on plants if they do not receive enough water. Dropping leaves is a defensive mechanism by the plant to conserve water because plants easily lose water through their leaves. If a plant remains without water long enough, all leaves will turn yellow and die, as will the entire plant. Our current drought conditions are certainly the cause of decline for many of our plants and trees. Environmental variables like heat spells, frosts, drying winds and sun burn can cause outdoor plants to become stressed, causing the leaves to yellow and drop. Once the environment becomes stable and the plant becomes acclimated, most plants should recover. Disease or pest infestation may also cause a plant’s leaves to turn yellow. Common pests notorious for this are spider mites, lace bugs and aphids. These small insects suck nutrients from leaves, stems and roots of a plant. Fungal infestations like root rot and virticillium wilt will also cause discoloration and dropping of leaves. Nematodes are microscopic worm-like creatures that attach themselves to roots and suck out moisture. A special soil test is usually required to determine if they are the problem for a dying plant. Nutrient deficiency will also cause yellowing of the leaves. This happens when the plant draws the nutrients the soil lacks from its own leaves. The most common deficiency is Nitrogen deficiency, which causes all leaves to turn light yellow and growth to be stunted. Iron deficiency causes yellowing between leaf veins, and potassium deficiency causes leaf tips to yellow and die-back.

Our current weather conditions are the major cause of plant and tree problems. Our sandy soil conditions add to the problem by not holding water long enough to satisfy the plant’s requirements. Normal hand watering from a garden hose simply isn’t enough. This type of irrigation usually dries before reaching the root system and does little to help the plant. Soaker hoses provide moisture where it is needed and can be left on for extended periods of time. Shallow rooted trees such as dogwood, Bradford pear, and river birch along with plants like azalea and boxwood require lots of water during hot and dry weather or they will show signs of wilting.

Earlier we mentioned that too much water can cause leaves to turn yellow. While almost all plants require a sufficient water supply to thrive, too much can kill the plant. The root system absorbs water along with oxygen to support plant growth and nutrition. If too much water accumulates in the root system, oxygen is cut off and the plant will begin to fail. Once the water level is normal the plant may recover and eventually get back to normal. Leaf yellowing is a symptom of something going wrong and can be caused by numerous things. A little detective work may be needed to determine the real cause.

The Master Gardeners will be at the Farmers Market on August 6, 2011 from 8 A.M. until noon to answer any gardening questions that you may have. The 2011 Aiken Gardening Almanac is about sold out. There are very few copies left and they will be available for $15 at the Farmers Market. The next Lunchbox Seminar will be held at noon on Monday, August 15, 2011 at the Clemson Extension office, 1555 Richland Avenue East. Aiken Master Gardener extraordinaire Jim Bennett will speak about “Cool Season Vegetables,” giving you all the information you need to start your fall and winter gardens. Jim is one of South Carolina’s best gardeners and an outstanding speaker. Don’t miss this special, free event.

The Clemson Extension office receives all types of calls about problems in the garden. One of the most common questions is “Why are my leaves turning yellow?” The question may refer to plant, tree or vegetable leaves, and the answer may be different for each type of plant. Let’s look at a few of the possibilities with the understanding that there could be more reasons than we can cover in our allowed space.

Too much water is the problem in the majority of cases when a plant’s health is declining. Several factors determine the appropriate frequency of watering: type of plant, temperature/humidity, pot size, light and drainage. Checking the plant on a regular basis instead of adhering to a strict schedule is better than overwatering, which drowns the roots. Some plants are heavier feeders than others and will need to be fed more often. Using a weakened solution of a soluble fertilizer when watering your plants is better than a strong dose every once in a while. Aphids, scale insects, mites and root damage due to fungal infections can cause yellowing of the leaves on houseplants. Mite infestation is facilitated by warm, dry environmental conditions. While most plants respond well to bright light, individual plants have different needs both for the amount and the intensity of the light they require to grow and thrive. Yellow leaves can indicate that your plant is either receiving too much or too little light. Investigate the proper light requirements for your specific plant. Yellow leaves, especially if they are on the lower portions of the plant, can be an indication that the roots are overgrown in the pot. Rubber plants are particularly prone to this problem. Some loss of foliage is normal. The length of time the leaves remain on the plant depends on the species.

There are many reasons why an outdoor plant’s leaves may turn yellow and possibly die. Sometimes this yellowing process is perfectly natural, and other times it is caused by environmental changes or pests. Every year in the fall, deciduous perennial plant species enter a state of dormancy, where they shut down their metabolism for the winter. As winter nears, plants and trees absorb the nutrients in their leaves, then shed the leaves to the ground below. With the coming of spring, deciduous plant come out of dormancy and grow new leaves for the coming year. Leaves may turn yellow on plants if they do not receive enough water.

Dropping leaves is a defensive mechanism by the plant to conserve water because plants easily lose water through their leaves. If a plant remains without water long enough, all leaves will turn yellow and die, as will the entire plant. Our current drought conditions are certainly the cause of decline for many of our plants and trees. Environmental variables like heat spells, frosts, drying winds and sun burn can cause outdoor plants to become stressed, causing the leaves to yellow and drop. Once the environment becomes stable and the plant becomes acclimated, most plants should recover.

Disease or pest infestation may also cause a plant’s leaves to turn yellow. Common pests notorious for this are spider mites, lace bugs and aphids. These small insects suck nutrients from leaves, stems and roots of a plant. Fungal infestations like root rot and virticillium wilt will also cause discoloration and dropping of leaves. Nematodes are microscopic worm-like creatures that attach themselves to roots and suck out moisture. A special soil test is usually required to determine if they are the problem for a dying plant. Nutrient deficiency will also cause yellowing of the leaves. This happens when the plant draws the nutrients the soil lacks from its own leaves. The most common deficiency is Nitrogen deficiency, which causes all leaves to turn light yellow and growth to be stunted. Iron deficiency causes yellowing between leaf veins, and potassium deficiency causes leaf tips to yellow and die-back.

Our current weather conditions are the major cause of plant and tree problems. Our sandy soil conditions add to the problem by not holding water long enough to satisfy the plant’s requirements. Normal hand watering from a garden hose simply isn’t enough. This type of irrigation usually dries before reaching the root system and does little to help the plant. Soaker hoses provide moisture where it is needed and can be left on for extended periods of time. Shallow rooted trees such as dogwood, Bradford pear, and river birch along with plants like azalea and boxwood require lots of water during hot and dry weather or they will show signs of wilting.

Earlier we mentioned that too much water can cause leaves to turn yellow. While almost all plants require a sufficient water supply to thrive, too much can kill the plant. The root system absorbs water along with oxygen to support plant growth and nutrition. If too much water accumulates in the root system, oxygen is cut off and the plant will begin to fail. Once the water level is normal the plant may recover and eventually get back to normal.

Leaf yellowing is a symptom of something going wrong and can be caused by numerous things. A little detective work may be needed to determine the real cause.

Why do leaves change color? It’s one of those questions – like, why is the sky blue? Most simply, to survive the winter, deciduous trees need to store nutrients in their roots, which means they must absorb the nutrients in their leaves. Changes in color are triggered as the trees absorb essential nutrients. Here’s how it works: Throughout the warm sunny months, trees are lush and green because they’re working hard. Tree leaves are green because the abundance of the pigment chlorophyll, which is essential to converting sunlight, water and carbon dioxide into energy-rich sugars. If plants hadn’t figured out the trick of photosynthesis, we’d all be out of luck, since the energy humans need to live comes from plants, or the animals that eat plants. Tree leaves are also busy using other essential nutrients, like nitrogen and phosphorus (the same main ingredients in most store-bought fertilizers, or in compost), so these nutrients are abundant in summer foliage. As summer wanes, changes in tree leaves are triggered by the cooler temperatures, changes in rainfall and weather, and most of all, the shortening of daylight hours. Much of the change happens without our knowing it, as trees begin to absorb essential nutrients and store them in their roots so they are available for the following spring. As the trees absorb the last of the chlorophyll, however, the brilliant colors we associate with autumn begin to appear. Eventually, the leaves lose their ability to stick to the branches, they wither, turn brown and fall to the earth. Another cycle is fulfilled and we wait for the warm temperatures of spring to start again.

Bill Hayes has been in Aiken since 1982 after moving from Chicago, Ill. He was in the chemical process industry for more than 40 years before retiring in 1999.

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