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Raspberries - Diseases, Pests and Problems



Basic Information



Problem: Anthracnose
Affected Area: Fungal Disease

Description: Red/purple spots appear on the stems and branches in the spring. As the disease gets worse the spots sink in and become little pockets that have turned to a light gray color. This can cause drying and cracking. The disease can also affect the leaves; which also get purple spots that progress to white spots. Fruit may be unfit for sale.

Control: Reducing overhead irrigation prevents the spread of the disease. Good air circulation and not allowing the plants to be wet for long frequent periods of time will reduce the disease. If the problem continues then the appropriate fungicides should be used.


Problem: Cane Blight
Affected Area: The disease affects the branches

Description: The disease occurs in connection with wounds. This disease usually cannot be detected from outside appearance. The disease is observed by scraping off the outside of the branches and looking at the inside. A brown sore will be seen spreading from the wound. As it spreads the buds may die and new shoots will wilt. Sometimes the entire area above the infected area may die.

Control: Overhead irrigation should be kept to a minimum during times of possible infection. The more water that splashes off the ground onto the plants the easier it is to spread the disease. Good circulation and sunlight are very important factors because they allow the plants to dry quickly. Try to keep from hurting the plants while moving through them or while using tools. The use of fungicides also helps control the fungi.


Problem: Midge Blight
Affected Area: The disease affects the branches

Description: The stems develop splits beneath swollen leaf bases. Midge larvae damage tissue in the slits and allow fungi to enter. The splits then turn dark colors of brown and purple. The splits will then widen and the inner parts of the branch are then exposed. This weakens the branch and it could break under any stress. Later in the growing season a second wave of midge larvae come through and infect the splits again and caused more damage to the branch which may even include the loss of buds.

Control: The actual damage is caused by the fungi that infect the branches but the cause is actually the midges. Fungicide may actually make the problem worse. Using insecticides will kill the midges and eliminate the problem.


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

Description: The leaves are infected at the outer edges and the disease moves inward. After taking over the leaf it spreads to the nodes on the branches and is viewed as a dark sore spreading over the branch. This can cause buds from growing in the spring and if they do it limits the number of flowers it will have.

Control: It is important to provide good airflow to the plants with good pruning and weeding. Using fungicides is an effective way of controlling the disease.


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

Description: The disease is recognized when light brown sores appear on older leaves and spread to the nodes. The leaf is usually shed soon after and the fungus travels rapidly around the branches. In the winter the sores are only visible as white/gray streaks. If the plant reaches the spring again the disease will be considerably worse and sores like black blisters will form.

Control: To keep the plants free of the fungus it is necessary to keep the plants well aired out and weed free. This will keep the plants dry and avoid fungus. The use of fungicides are also recommended to aid in controlling the disease.


Problem: Raspberry Leaf Spot
Affected Area: leaves

Description: Only on Raspberries. The new leaves of the plant develop greenish black spots. As the leaves get older the spots turn a white/gray color. These spots often drop out creating holes in the leaves. If the plant is infected severely the leaves will fall off early creating bare plants.

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: Raspberry Mosaic Disease Complex
Affected Area: leaves and fruit

Description: The leaves blister up and the plant gets smaller. These plants are often damaged more in the winter than health plants. Not as much fruit is produced and the fruit that is produced is a really poor quality.

Control: Aphid sprays are generally not very effective. The most effective thing is to plant plants that are resistant to the virus. It is also a good idea to plant new fields away from sites where the virus has been known to have occurred.


Problem: Raspberry Leaf Curl
Affected Area: branched, fruit, and leave

Description: The leaves and branches of the plants become twisted and turn a whitish bleached color. The new branches are very short and may be in large clusters. The fruit is poor quality; often very crumbly and seedy. The leaves become very small and greasy.

Control: Keep wild plants away from healthy plants. The new planted should be kept away from areas where the disease has been in he past. Using aphid sprays may help to control the spread of the virus but by the time you notice the virus it is often too late.


Problem: Raspberry Vein Chlorosis
Affected Area: Leaves

Description: The leaf veins turn white and the leaf may also become distorted. This disease and cause the plants to be shorter and become ripe earlier.

Control: There are certain types of plants that are unaffected by the virus.


Problem: Raspberry Bushy Dwarf
Affected Area: fruit, leaves, and branch

Description: The fruit may become crumbly when infected. The leaves may develop rings and lines and the veins may become white. The plant may also be smaller than usual and very bushy.

Control: The only was to control the virus is to use plants that are immune to it.


Problem: Raspberry Crown Borer
Affected Area: crown of the plant

Description: This is a moth that looks like a yellow jacket and lays eggs on the underside of leaves. When these eggs hatch the larvae move down the plant to the base just under the ground. The larvae then did many little holes in the plant and cause large amounts of damage. The larvae are very small and white with brown heads.

Control: Removing wild berry plants helps control the pests. Treat the plants with insecticides that drench the plants in order to kill the larvae. It may have to be done several times.


Problem: Raspberry Bud Moth
Affected Area: buds

Description: The larvae of the moth attack the unopened bud and tunnel inside and destroy it. The larvae can cause very extensive damage to the plants. The plants may not grow any fruit.

Control: The use of insecticides will control the larvae very well. There won?t be any problems as long as the insecticides are applied frequently.


Problem: Raspberry Fruitworms
Affected Area: leaves and fruit

Description: Small yellow/white larvae are often seen clinging to the harvested fruit. These larvae will burrow into the fruit and destroy it. Often there will be holes in the leaves of the plants indicating the presence of adult beetles.

Control: Insecticides are used primarily to control the insects.


Problem: Excessive Moisture
Affected Area: Affects the entire plant

Description: Many types of root rot can occur as well as fungus spreading up the plant. The plant can drown because when the soil is soaked there is not oxygen in the soil that the plants need.

Control: Good drainage can solve the problem.


Problem: Insufficient Moisture
Affected Area: entire plant

Description: The branches and fruit will not grow well at all. The plants will wilt. The fruit will be small and crumbly. The leaves will eventually turn brown and the entire plant will die.

Control: Using irrigation that runs down the row is the best way to avoid this problem.


Problem: Earwigs
Affected Area: Leaf

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 materilas, 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: Leaf

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: Leaf

Description: Tops of canes die back in mid-summer. 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: Leaf

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: Leaf

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

Control: Dispose of affected plants





Raspberries

Tips

Raspberries are very prone to virus diseases. Always purchase certified virus-free plants.

 

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