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Blackberries - Diseases, Pests and Problems



Basic Information



Problem: Purple Blotch
Affected Area: The disease affects the branches

Description: Small, dark green sores appear on the branches near the ground. As it gets worse the disease will spread up the plant. The sores turn red and then brown as the disease gets worse. They also get bigger. The disease is often confused with frost damage in the spring. The disease can leave whole shoots without leaves.

Control: Plant healthy plants that have not been grown around wild blackberries. Branches that have the disease should be removed and burned. Spraying fungicides has also proven effective.


Problem: Botryosphaeria Cane Canker of Blackberry
Affected Area: The disease affects the branches

Description: Sores appear around the buds on the main stems and are recognized by their red/brown discolorations. The infected part is not usually killed. The sores often form at places where the branch had been wounded. The disease is most noticed as the fruit ripens because the leaves in the infected portion will begin to wilt and often the infected branch produces less fruit if any at all. If the disease progresses it can split the branch open.

Control: Start berry patches by using disease free plants from a nursery. Fertilize the new plants well but pay attention not to be excessive, especially with the nitrogen. Some kinds of berry plants are more resistant to the disease than others.


Problem: Rosette Double Blossom
Affected Area: buds

Description: The entire appearance of the plant changes because of this disease. Buds are usually infected in the summer but don?t show signs of infection until the following spring. Many small leafy branches will come from each bud and will be far shorter and lighter in color than normal shoots. The flower buds are usually longer and redder than usual and when the flower actually comes out it is usually larger and twisted giving the appearance of two blossoms. Fruit quality is very poor if there is any at all.

Control: Uninfected plants from a nursery should be used to plant the new berry patches and should be located away from any wild berry patches. The infected new clusters of shoots and blossoms can be hand picked to control the disease. The use of fungicides can also help control the spread of the fungus. Removing old branches is a good idea to help prevent the disease.


Problem: Downy Mildew
Affected Area: leaves

Description: When the leaves get infected they turn yellow at first which then progresses to a red/purple color. The color sometimes appears as blotchy spots across the leaf surface. Light pink/brown spots appear on the bottom of the leaf below the upper spots. As the disease gets worse the spots on the leaves will turn brown with yellow edges. The leaves may fall off early and the fruit will appear very dull instead of having a shiny appearance.

Control: Disease-free plants should be used to create new patches in places that have never had the disease. Chemical removal of suckers helps keep the disease from being introduced to the plants. Reducing the amount of moisture that remains in the patches for long periods of time will eliminate good conditions for the fungus. Removing old branches and spraying with fungicides will also help in controlling the disease.


Problem: Powdery Mildew
Affected Area: Entire Plant

Description: Leaves infected by the disease have light green spots on the top and white spots on the bottom beneath the green spots. The leaves will appear to be soaked and soggy. When the disease becomes worse the shoots become long and twisted. The fruit can also become covered with a white fungus.

Control: Certain types of berry plants are more resistant to the virus than others. It is good to remove all suckers that have symptoms of the disease. Cutting the plant back in the spring also reduces the chance of becoming infected. Good air circulation combined with the use of appropriate fungicides also help in controlling the fungus.


Problem: Septoria Leaf Spot of Blackberry
Affected Area: The disease affects the leaves

Description: The infected leaves develop white spots with a brown edge. The disease can cause the leaves to fall off early.

Control: Make sure that the plants have good air circulation. Pruning the plants and removing old and death branches will help control the fungus. Appropriate fungicide use is also recommended


Problem: Botrytis Fruit Rot
Affected Area: The disease affects the entire plant

Description: The infected branches first show symptoms when black spots appear on the outer surface. The disease attacks the flowers once they have opened. The flower dies and becomes a perfect place for the fungus to grow. The fruit that is infected may have the rot anywhere but it usually begins near the attachment to the stalk. The entire fruit can become covered with a gray mold and if not removed can become stuck to the branch.

Control: Fungicides should be used as a main source of control. Creating a patch with good air flow is very important in controlling how much moisture remains around the plants. Good pruning techniques will aid in controlling the disease also. There are some strains of berries that are resistant to the fungus. Picking the raspberries at the correct stage of ripeness is very important to keep them from becoming moldy.


Problem: Postharvest Soft Rot
Affected Area: The disease affects the entire fruit

Description: The disease usually only directly affects mature or damaged fruit. The berries may become soggy with fungus growing on the outside. This usually happens in storage.

Control: There are no fungicides or other chemicals that can help treat this disease. The disease is controlled through good care of the plants themselves. Good air circulation is very important to keep the plant from staying wet all the time. The fruit should be picked at the moment it is ripe and then stored in a cold area with decreased oxygen levels and increased carbon dioxide.


Problem: Stamen Blight
Affected Area: The disease affects the flowers

Description: Infected flowers are distinguished from healthy flowers by noticing that the bad ones have a white powdery appearance. The Stamen will often lie down on the petals and make the flower look much larger than the other healthy ones. The diseased flowers create fruit that is difficult to harvest because it is attached to the branch very securely and it is damaged by removing it.

Control: It is recommended that disease-free plants should be used to start berry patches. It is important not to have any wild berries mixed in. Fungicides can reduce the disease greatly.


Problem: Orange Rust
Affected Area: The disease affects the leaves

Description: The disease can be detected very early because the new growth will be clustered together in twisted bunches. The leaves are usually odd shapes that are a yellowish color. The leaf tissue will turn white with black specks which soon turn into blister-like bubbles. These bubbles then rupture and turn bright orange.

Control: It is important to plant good healthy plants and take out any wild plants. Removing any plants that show symptoms of the rust in the spring will help minimize the damage later on. As the plants grow it is also necessary to look through the plants to locate and remove any leaves that have the blister-like bubbles. Air circulation is also very important. Fungicides may be useful in controlling the disease.


Problem: Cane and Leaf Rust
Affected Area: The disease affects the branches and leaves

Description: Yellow material builds up on the outside of the branches and splits the bark. As this disease continues to get worse the leaves of the plants may begin to fall off early. Rarely affects the fruit.

Control: Old branches that have had the disease should be removed. The use of fungicides are very effective for controlling the disease.


Problem: Yellow Rust
Affected Area: entire plant

Description: Bright orange material builds up on the surface of the leaves and the shoots near the ground. The fungus also can be seen as yellow patches on the buds and fruit as well. Infected branches can split and break.

Control: Certain types of raspberry plants are resistant to the fungus and should be used in areas where the disease occurs. Increasing air circulation as well as removing any dead branches and actively removing any other branches that show symptoms of the disease is one of the most effective ways to control the disease.


Problem: Late Leaf Rust
Affected Area: The disease affects the leaves and fruit

Description: A lot of little yellow spots form and then turn brown as the leaf is dying. Small yellow pockets form on the underside of the leaf. This can cause the leaves to fall off early and damage the branches. The fruit will also develop yellow patches that make them unfit for sale.

Control: Increasing the airflow allowing the plants to dry more quickly is vital in controlling the disease. Removing dead leaves and branches in the fall will also help in the control. Fungicides may be of some use but have not shown significant results in the past.


Problem: Blackberry Rust
Affected Area: The disease affects the entire plant

Description: The rust can affect the entire plant but is most noticeable on the leaves. Yellowish/red patches appear on the tops of the leaves. In several days the patches turn into round purple or red spots. These spots will then develop yellow or brown centers. On the bottom of the leaf patches of yellow fungus form that is very powdery. In some cases the entire leaf turns white and falls off the branch.

Control: Control methods include creating good airflow between the plants and the use of appropriate fungicides.


Problem: Phytophthora Root Rot
Affected Area: The disease affects the branches

Description: The disease most often strikes at the lowest points in the field. New branches often wilt and die soon in the spring. Sometimes the disease moves more slowly and the branches slowly turn white and wilt during the summer. Other times the disease doesn?t even become present until the next year.

Control: Good drainage is necessary in controlling the disease. Certain types of plants are resistant to the disease. The use of fungicides and fumigants may also be of assistance in efforts to eliminate the fungus.


Problem: Verticillium Wilt
Affected Area: The disease affects the leaves and branches

Description: The disease makes the leaves turn a pale color in the summer and then appear to become better in the fall. The next spring the leaves turn yellow and die. The branches will turn completely blue on one side before they shrivel and die. On blackberries the branches don?t turn blue but they do end up collapsing.

Control: Crop rotation as well as the use of fungicides is recommended for controlling the disease.


Problem: Armillaria Root Rot
Affected Area: The disease affects the roots

Description: The top of the plant decreases in growth and dies and the roots and crown of the plant are killed. White or yellow fungus appears on the roots in sheets. The fungus can also appear to be roots itself. In the fall the fungus can actually be seen around the base of the plant.

Control: Find the source of infection and then remove all infected plants including all of the roots. After this has been done the ground should be treated with fumigants. This should provide good control of the fungus.


Problem: Fire Blight
Affected Area: The disease affects the branches and leaves

Description: The infection usually is visible first at the tip of the branch and then continues downward. The disease surround the entire branch and causes it to die, becoming purplish/black and curling up. The branches often have sticky liquids seeping out of wounds.

Control: There is not specific control method that works very well to control this disease. Removing the diseased plants and increasing the air circulation is recommended.


Problem: Rubus Stunt
Affected Area: The disease affects the branches and leaves

Description: Many short, thin shoots are produced and the leaves are often spotted. It usually takes a year after the plant has been infected for the symptoms to show up.

Control: Plant only good healthy plants. The use of insecticides that will destroy the eggs as well as the insects are necessary so that the eggs of the insects do not survive over the winter and hatch in the spring.


Problem: European Nepovirus Diseases
Affected Area: The disease affects the leaves and growth

Description: The leaves develop yellow specks and yellow veins as well as becoming a little distorted with downward curling. The plant growth may stop or slow down considerably and will produce little or no fruit.

Control: Use plants that are healthy and virus free. The use of fumigants to kill the nematodes is often used. Controlling the weeds as well as rotating the crops also reduces the chance of nematodes in the fields.


Problem: Tomato Ringspot
Affected Area: The disease affects the leaves

Description: The leaves may take a few weeks longer to form and they might have yellow rings, lines, and white veins. The plant will become very week and will be very small. In some types of plants the fruit yield is affected considerably.

Control: Use plants that are know to be free of the virus. Test the soil for nematodes before planting and use fumigants on the soil. Controlling the weeds will also help control the disease.


Problem: Blackberry Calico
Affected Area: The disease affects the leaves

Description: White spots appear on the leaves which are followed by small yellow spots to yellow rings and lines. When the disease gets bad the leaves may turn a reddish color and begin bleaching and die.

Control: Usually growers don?t pay attention to this disease because it really doesn?t do much damage in large areas and is very sporadic. Heat treating the plants for long periods has been shown to eliminate the disease.


Problem: Tobacco Streak
Affected Area: The disease affects the leaves

Description: Small, white, dead rings appear on the leaves. As the disease progresses the tips of the new branches die.

Control: Use plants that are initially free of the virus to start new plantings. Remove old branches. Do not plant Raspberry plants near other berry plants and the risk of infection will be reduced considerably.


Problem: Root-Lesion Nematodes
Affected Area: roots

Description: The symptoms are very hard to notice at first because they are very small sores on the roots. As the nematodes increase the damage on the roots increases. Eventually only the main roots remain. The plant itself usually sees a great decrease in growth and fruit size. Many buds die during the winter.

Control: Only nematode free plants should be planted. Before you plant it is a good idea to fumigate the ground. After the plants have been planted chemicals used specifically to kills nematodes can be used.


Problem: Dagger and Needle Nematodes
Affected Area: The damage affects he roots.

Description: The damage is noticed when round bumps appear on the roots. The roots will also begin to swell up and the ends may curl up. The damage on the roots affects the growth of the branches and the fruit becomes crumbly.

Control: There are some types of plants that are resistant to the nematodes. It is also necessary to fumigate the ground before planting.


Problem: Strawberry Crown Moth
Affected Area: The damage is done to the roots and crown.

Description: The moth larvae feed on the roots and crown and that is what injures the plant. The plant usually grows very slowly and turns more of a yellow color. The leaves also fall off prematurely.

Control: If plants are not infested very badly then the infected plants should just be removed. Don?t plant the plants next to Strawberry plants that are infested. There are also moth traps that attract and kill the moths. Insecticides have also been used to control the problem.


Problem: Japanese Beetle
Affected Area: The damage affects the roots, leaves, and fruit.

Description: The larvae will feed on the roots and cause damage in that area. The adults on the other hand feed on the leaves and fruit. This does considerable damage to the plants.

Control: Insecticides control the insects better than anything else.


Problem: Rose Chafer
Affected Area: flowers, leaves, and fruit

Description: The insects are noticed the most in very sandy soils where they multiply very rapidly. They attack the flowers primarily, often destroying the entire flower. This results in low numbers of fruit. The insects can also damage the leaves and fruit as well.

Control: Insecticides should be applied weekly and the ground should be tilled and turned over regularly after heavy rains.


Problem: Lygus Bugs
Affected Area: The damage affects the flowers, branches, and frui

Description: The insect feeds on the flowers, tips of new shoots, and developing fruit. The insect can kill the new shoots or make them branch out. The flowers can be completely destroyed and reduce the fruit yield considerably. The fruit can also be attacked and destroyed.

Control: Using insecticides as well as keeping the area well weeded should control the insects.


Problem: Picnic Beetles
Affected Area: Fruit

Description: The beetles bore into ripe fruit especially if it is a little overripe. The beetles will eat part of the fruit and then leave the fruit looking bad. Often the beetles also produce wastes that cause the fruit to rot very quickly.

Control: Insecticides should not be used because they will leave a residue on the fruit. The best way to control the insects is to make sure that overripe fruit does not accumulate in the fields and all damaged fruit should be removed as well. After harvest the berries should be removed from the field as soon as possible and covered as well.


Problem: Climbing Cutworms
Affected Area: The damage affects the new growth and fruit.

Description: Larvae present at the end of the winter climb up the new shoots and eat the new tissue in the buds. The entire plant may loose all of it leaves. The worms are also knocked loose during harvest and contaminate the harvested fruit.

Control: Insecticides are the main way to control the worms. The insecticides should be applied after dark when the worms are feeding. During harvest the worms should be picked out of the berries and then killed.


Problem: Blackberry Psyllid
Affected Area: The damage affects the entire plant.

Description: The growth of the plant becomes distorted and the leaves curl up, the plant may stop growing, branches may become weird shapes, and the color of the plant will not be normal. Sometimes the fruit may also be affected.

Control: This insect is only a problem when the plants are planted next to conifers. Remove infected branches and use insecticides to control the insects.


Problem: Western Winter Moth
Affected Area: The damage affects the buds and blossoms.

Description: The moth larvae feed on the buds and blossoms in the spring. The leaves and flowers usually are webbed together with silk. The larvae then burrow through the bud.

Control: Controlling the larvae is done by applying insecticides.


Problem: Rednecked Cane Borer
Affected Area: branches

Description: The insect feeds on the inside of the main branches and causes the branch to either die or become very weak and break when the fruit becomes ripe. These branches are also easily damaged in the winter.

Control: The insect is usually detected during the winter pruning. Insecticides should be used at the first bloom in the spring. The insecticides should be applied to the base of the branches because the flower can become infected and bees will die.


Problem: Low-Temperature Injury
Affected Area: Affects the entire plant

Description: Low temperatures in the spring or early summer can kill the buds and stop new shoots from growing or fruit from forming. When the temperature fluctuates in the winter it can often caused damage to the buds and branches. The plants can actually be more prone to getting different kinds of fungus if they are damaged by extreme cold in the winter.

Control: Some berry plants are more resistant to changes in temperature than others. Covering the plants in the spring when it gets cold can help reduce the chance of damage.


Problem: High-Temperature Injury
Affected Area: Affects the entire plant

Description: Too much heat can kill the buds. It can also cause the fruit to ripen to early and it can cause the fruit to break apart. The heat can also cause droughts which will kill the plants.

Control: Keep the plants well watered and make sure not to leave ripe fruit unpicked.


Problem: Wind
Affected Area: Affects the branches of the plant

Description: The branches can break and snap off. Branches rubbing against each other can create cuts in the branches and lead to infection or girdling. The plants can also just totally fall over.

Control: Create wind breaks in hard wind. Having something for the plant to lean against for support is also recommended.


Problem: Earwigs
Affected Area: Leaves

Description: Reddish-brown elongated insects up to 1" long with pincers up to 1/4 inch long. Adult have two pairs of small wings but rarely fly. Earwigs are nocturnal hiding in convenient, dark cook place during the day and emerging at night. They feed primarily on decaying materials, but also attack fruits, blossoms and vegetables

Control: Yard sanitation. Remove surface debris which provides shelter. Spray with *Sevin (do not spray blooming plants) or *Malathion. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Grasshoppers
Affected Area: Leaves

Description: Long jumping insects, which may develop wings on adulthood. Have a voracious appetite for leaves, fruits and vegetables. Often abound in weeded areas moving into the garden to feed. Lay eggs which winter over and hatch out in the spring in undisturbed soil. Newly hatched grasshoppers are about 1/4 to 3/8 inch long. They do not develop wings until they have passed through four to five immature stages.

Control: Cultural controls are important to limit grasshoppers. The insects are most abundant in undisturbed areas such as fields of dry grass, along fences, in ornamentals, and in weed patches. Control weeds by tilling or mowing and spray in these areas to reduce grasshopper infestations. Tilling or otherwise working the soil interrupts the grasshopper's life cycle. This is especially effective right after harvest in the fall. It stirs up the eggs, moving them deeper into the soil where they will not hatch or brings them to the surface where birds eat them or frost, sun and wind destroy them. Tilling is still of value in the spring. Grasshoppers seek undisturbed soil to lay their eggs, so tilled soil is unattractive to egg-laying. Till unused strips of ground surrounding the landscape to keep the insects at bay. Chemical controls are most effective on young insects. They become less susceptible as they pass through each stage until they develop adult wings. With wings they develop mobility and become more difficult to treat. Concentrate sprays in shady areas, weedy areas, and bushes where hoppers are concentrated. *Diazinon can be used on most edible crops. It is most effective on newly hatched or small grasshoppers. It's residual action lasts one to two weeks. *Malathion destroys insects quickly but its residual effect lasts just a few days. It is safe to use on food crops within a few days of harvest. *Sevin, which lasts longer than malathion, is very effective on grasshoppers, but particularly hazardous to bees. The product can be carried into the hive where it spreads the damage among these beneficial insects. Never spray sevin while plants are in bloom. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Cane Borers
Affected Area: Stem

Description: Tops of canes die back in midsummer. Cane hollowed out when borer is active.

Control: Spray with *sevin (Never spray blooming plants) * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Powdery Mildew
Affected Area: Leaves

Description: White powdery substance on leaves.

Control: Use surface or underground watering methods to avoid wetting leaves. * Apply benomyl or sulfur as disease appears. *Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Virus Diseases
Affected Area: Leaves

Description: Plants begin to fail and leaves yellow and curl.

Control: Dispose of affected plants





Blackberries

Tips

Using black plastic mulch provides needed water retention and discourages slugs and snails.

 

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