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Strawberries - Diseases, Pests and Problems



Basic Information



Problem: Frost Injury
Affected Area: Weather injury that affects the flowers, pistils,

Description: Frost injury kills the pistils causing the flowers to turn black. In severe conditions, the flower may die or a few pistils may survive and the flower may produce deformed fruit.

Control: Overhead irrigation and plastic tarps can be used to prevent frost damage.


Problem: Winter Injury
Affected Area: Weather injury that affects the entire plant.

Description: Winter injury results when ice crystals are formed at the base of the plant. The plant will lose its vigor, become more susceptible to diseases, and turn brown at the base by the crown.

Control: Winter injury can be prevented by insulating the plants with mulches and selecting a variety of plant that are good for the specific climatic region.


Problem: Lightning Damage
Affected Area: Weather injury that affects the entire plant.

Description: Lightning damage in strawberry fields can be easily detected by the circular areas that are dead or dying and the outer areas of plants that have darkened leaves.

Control: Lightning damage cannot be controlled or prevented.


Problem: Hail Injury
Affected Area: Weather injury that affects the entire plant.

Description: Hail injury is very detrimental during the flowering season and while the fruit is maturing. The fruit can be knocked of the plant or bruised and scarred with brown spots and the leaves many times are battered and scarred.

Control: Hail injury cannot be controlled or prevented


Problem: Nitrogen
Affected Area: Nutrient problem that affects the entire plant

Description: Nitrogen is needed in large amounts for strawberry plants. The lack on the required amount of nitrogen in strawberry plants results in smaller fruits, fewer runner, and the older leaves turn orange or red, while the younger ones are shorter and are a pale green color. Excess nitrogen will cause the quality of fruit to decrease and other diseases to increase.

Control: Soil tests can be taken to see if there is a proper amount of available nitrogen in the soil, but the availability often fluctuates and more can be added as needed.


Problem: Potassium
Affected Area: Nutrient problem that affects the entire plant

Description: Symptoms of potassium deficiency are rough edges of the older leaves, dark leaflets, wilted leaves in high temperatures and softened fruit as well.

Control: Soil tests can be taken to see if the potassium is at the proper level and more can be added as needed. Potassium bicarbonate is an effective foliar spray that can be added to prevent other diseases and give the needed potassium to the plant.


Problem: Boron
Affected Area: Nutrient deficiency and toxicity that affects the

Description: Symptoms of boron deficiency are slow root growth, deformed berries, and lop sided leaves. Symptoms of toxicity are hard, yellow berries, and rough leaf edges.

Control: Boron can be controlled by taking soil samples and keeping it in a range that neither toxic nor deficient to the plant.


Problem: Problems Caused by Weeds and Herbicides
Affected Area: Weed and herbicide injury affects the entire plant

Description: Weeds become problems in strawberries creating competition with the desired plants and negative aesthetic appeal, which then requires time and money to control. Herbicides can damage the leaves, roots, and the entire plant often killing it if not used properly.

Control: Weeds can be eliminated using cultural, biological, mechanical, and chemical controls. The most common are the mechanical and chemical controls such as cultivation, hand weeding, selective herbicides, and pre-plant and post emergence herbicides. The timing is very important with herbicides as well as choosing the proper herbicide and using the correct rate.


Problem: Angular leaf spot
Affected Area: Disease of the leaf caused by bacteria

Description: Angular leaf spot generally first appears as water soaked spots on the leaves. The leaf tends to turn translucent, later reddish brown spots appear, and the plant dies.

Control: The best control measures are to avoid overhead irrigation when possible and use clean planting stock. Other control measures are available such as antibiotics and copper-containing pesticides, but can cause phytotoxicity.


Problem: Powdery Mildew
Affected Area: Disease of the leaf caused by fungi

Description: White powdery spots appear on the undersides of the leaves. The white spots become bigger and eventually cover the whole underside of the leaf and the leaf itself begins to roll up. Purple/reddish blotches may begin to form on the upper and lower leaves. Fruit may become deformed and the plants may not produce well.

Control: Some controls may include using protective fungicides, resistant plants, and avoiding overhead irrigation if possible.


Problem: Phomopsis Leaf Blight
Affected Area:

Description: The symptoms first include five or six circular purplish spots and later combine along the veins to make large V-shaped areas that turn dark brown and black and die off.

Control: Some control measures that can be taken are removing older and infected leaves to help the foliar fungicide to be more effective.


Problem: Leaf Spot
Affected Area:

Description: Leaf spot is one of the most common diseases in strawberries. It is also known as Mycosphaerella leaf spot, Ramularia leaf spot, ?rust,? bird?s-eye spot, ?gray spotness,? and white spot. Leaf spot usually occurs in the springtime with wet cool weather and the symptoms generally include small lesions or spots, which become larger and start with a purplish color and change to red, brown, gray and eventually white.

Control: Control measures include selecting certain varieties that are more resistant than others. Common fungicide sprays may be used to reduce the symptoms and prevent disease buildup.


Problem: Rhizoctonia Leaf Blight (Web Blight)
Affected Area:

Description: This disease attacks older leaves and leaves a grayish or black color. Younger leaves become deformed and curled. High soil moisture levels and relative humidity are the main causes of this disease.

Control: Some control measures may in include avoiding sprinkler irrigation and using alternative irrigation methods.


Problem: Botrytis Fruit Rot (Gray Mold and Blossom Blight)
Affected Area:

Description: Botrytis fruit rot is generally noticed on ripening or ripened fruit, but can also occur on blossoms or premature fruit. This disease tends to develop on cool wet climates. Affected blossoms turn brown and die off. Symptoms of rotting occur on the fruit with browning of the tissue that spreads over the entire fruit and can cause the fruit to die before maturity. The rotted fruit will eventually become hard, tough, and dry. Some varieties are partially resistant to the this disease.

Control: Treating transplants with fungicides, spraying fungicides during the flowering period, and reducing injury during and after harvest are some of the best control measures for this disease.


Problem: Anthracnose Fruit Rot (Black Spot)
Affected Area:

Description: Anthracnose fruit rot occurs during harvest time with rainy warm conditions. Some of the symptoms of fruit rot start with water soaked spots forming on the growing fruit. The spots start with a light brown color and change to dark brown or black. Under humid conditions pick and orange spots may cover the existing spots. This disease also affects flowers. Open flowers quickly die and dry out, while flower buds that are just emerging have their petals burnt on the tips. The resulting fruit is usually small and hard with some deformities.

Control: Some controls may be implemented by establishing new plantings with anthracnose-free plants, drip irrigation, and using straw mulch between rows.


Problem: Leather rot
Affected Area: Disease of the fruit caused by fungi

Description: Symptoms of leather rot on premature fruit show brown spots on the fruit and then spreads to eventually cover the entire fruit and give it a leathery rough look. Infection of mature fruit may cause brown or purple colors to appear, and the fruit begins to decay giving it a bad odor and taste.

Control: Cultural controls for leather rot can include proper site selection for planting and reducing standing water or excess water in the field. Fungicides may also be used to reduce and rid an area of leather rot.


Problem: Phomopsis Soft Rot
Affected Area: Disease of the fruit caused by fungi

Description: Symptoms of phomopsis soft rot generally occur on mature ripening fruit. Brown spots occur on the fruit with a light brown color on the edges and a darker brown toward the center and it being crusty.

Control: No specific controls have been found for this disease.


Problem: Mucor Fruit Rot
Affected Area: Disease of the fruit caused by fungi

Description: Enzymes are produced from the fungus that attacks the mature fruit and causes the fruit tissue to deteriorate.

Control: The best way to control the fruit rot is to remove any ripened fruit and use proper fungicides and keep all harvesting and handling areas sanitary.


Problem: Red Stele Root Rot
Affected Area: Disease of the root and crown caused by fungi

Description: Depending on the severity of the infected plant red stele rot can show different symptoms. A severely infected plant will show signs that are visible above ground which include stunted growth with little or no fruit and wilting in hot weather. The younger leaves may turn bluish green and the older leaves may become red, yellow, or orange. Less infected plants will not show many above ground symptoms the main root will start to rot and red discoloration will appear on the root.

Control: To control red stele root rot it is best to select varieties of plants that have been inspected and certified disease free. Avoid planting in low wet spots and in soil with poor drainage. Some varieties of plants are resistant to red stele rot, but can become susceptible to the disease after time. Some fungicides have proven to work to prevent this disease.


Problem: Rhizoctonia solani Root Rot
Affected Area: Disease of the root and crown caused by fungi

Description: Symptoms of this disease include collapsing of the plant in the early part of the fruiting period, purple coloring, and curling up of the underside of the leaves. The petiole, or the part connecting the leaf to the stem, turns brown and the crowns are killed along with some of the smaller roots.

Control: Some soil fumigants have proven to be effective to rid an area of this disease.


Problem: Strawberry Mottle Virus
Affected Area: Aphid-borne virus affects the entire plant

Description: Symptoms of this virus include mottle and slight distortion of the leaves, along with stunted growth of the plant.

Control: Several control methods for this virus include the use of certified virus-free plants, aphid control, and avoid planting close to infected areas.


Problem: Tomato Ring Spot Nepovirus
Affected Area: Nepovirus that affects the entire plant

Description: Symptoms of this virus may include stunted growth, reduction in the number of runners, and the eventual death of the leaves and plant.

Control: Certified virus-free plants can be used to reduce the virus and stop it from spreading. Also soil fumigants can be used to rid an area of nematodes, which help spread and maintain the virus in the soil.


Problem: Strawberry Pallidosis
Affected Area: leaves

Description: Symptoms of this disease include leaflet distortion and small growth of the plants.

Control: Using disease free plants is the most effective way of eliminating this disease.


Problem: Strawberry Aster Yellows
Affected Area: entire plant

Description: Symptoms of this disease include stunted growth and cupping of the young leaves and deformities of the fruits.

Control: Heat treatment can help control this disease.


Problem: Phytoplasma Yellows
Affected Area: entire plant

Description: Symptoms of this disease include purple and bronze colored leaves, stunted growth and whitening of the leaves. The plant will usually die shortly after the symptoms show up.

Control: No specific controls have been found for this disease.


Problem: Summer Dwarf
Affected Area: leaves and fruit

Description: Symptoms of this disease include cupping and stunted growth of younger leaves while older leaves remain unaffected. The fruit may become deformed in the maturing process.

Control: Controls for this specific disease include planting nematode-free plants, using heat therapy, and finding the affected plants and talking them out and destroying them.


Problem: Root-Lesion Nematode
Affected Area: root

Description: Symptoms of root-lesion nematodes include brown spots and/or complete blackening of the roots.

Control: Soil fumigation is the most effective control measure


Problem: Sting Nematode
Affected Area: entire plant.

Description: Symptoms of the sting nematode include stunted growth, course roots with blunt tips, black spots on the roots, and few fine roots.

Control: Some common controls of sting nematode include fumigants, nonfumigant nematicides, and using different types of plants in the planting areas.


Problem: Dagger and Needle Nematode
Affected Area: roots.

Description: Symptoms of dagger and needle nematode include enlarged growths at the ends of the roots, stunted plant growth, and reduced runner production.

Control: Most fumigants that are used for other nematode related disease can be used to treat dagger and needle nematode.


Problem: Strawberry Aphids
Affected Area: Can cause various diseases

Description: Strawberry aphids can be found in any type of region where strawberries are grown. The aphids that attack strawberries are soft-bodied insects. Pale green aphids are the wingless form and are females and the light green ones are the winged aphids. They are most numerous in the spring and fall because of the hot dry climate during the summer months. They also can produce several generations through the growing season.

Control: Using the proper insecticides in the proper conditions and environments can control strawberry aphids.


Problem: Strawberry Root Aphid
Affected Area: Affects the entire plant

Description: Strawberry root aphids are a soft-bodied insect about 2 mm long. The aphid can vary in color from a pale green to a bluish black. Strawberry root aphids can be distinguished from strawberry aphids by their bluish color and short egg shaped bodies. These aphids usually attack and eat the leaves and stems of the plant and then are carried or transferred down to the roots by ants allowing the aphids to suck the sap from the tissues of the root. The plant will then turn very pale and look unhealthy, producing small fruit.

Control: Using aphidcides for the aphids above ground and tilling the soil deep before planting to control the ants that help the aphids survive below ground are effective controls for the strawberry root aphid.


Problem: Cyclamen Mite
Affected Area: Affects the above ground portion of the plant

Description: The cyclamen mite is very small and difficult to see with the naked eye. The cyclamen mite feeds on leaves near the crown of the plant until the leaves become stunted, crinkled, and deformed. When the leaves become brown and dry and the mites move to the flowers causing them to die. The fruit produced from the infested plants are cracked, distorted, bronzed, and the seeds stick out of the flesh of the fruit.

Control: Infected plants can be removed and destroyed when found preventing the spread on the mite. No other specific control has been found to prevent the cyclamen mite.


Problem: Spider Mites
Affected Area: Insect that affects the above ground portion of th

Description: Spider mites begin to attack the undersides of young strawberry leaves in the early spring. The top of the leaves may produce small, yellow spots after they are infected. The yellow spots do not always appear late in the season, but the browning and drying out of the lower surface of the infected leaves are the most prevalent symptoms.

Control: Spider mites can be controlled by naturally by predators that live in the soil and by wet, cool weather conditions. Pesticides are not very effective and can cause negative effects on native predator mites.


Problem: Lygus Bugs
Affected Area: Insect that effects the fruit of the plant

Description: Lygus bugs are about 6-6.5 mm long and oval and are a greenish or brownish with reddish brown marking of the wings. Some lygus bugs have a small yellow triangle on the back. The bugs attack the seeds of the fruit by puncturing them stopping the development of the fruit in the infected area.

Control: Insecticides and weed control around the plants can be used to control lygus bugs.


Problem: Strawberry Bud Weevil
Affected Area: Insect that affects the buds of the plant

Description: Strawberry bud weevils are a dark reddish color and about 2.5 mm long. The weevils feed on pollen from the blossom buds that they get through puncturing the buds. The female then leaves an egg inside the bud leaving it to hatch.

Control: Rotating strawberry patches at least every three years and tilling the areas after the growing season can help reduce the infestation of the strawberry bud weevil.


Problem: Spittlebugs
Affected Area: Insect that affects the above ground portion of th

Description: Spittlebugs bury themselves in a saliva-like mass and the secretion that they give off inhibits strawberry pickers to get the fruit. The spittlebugs feed on the plants juices at the base of the plant and move up to the more tender parts of the plant.

Control: Insecticides can be used to effectively spittlebugs.


Problem: Chewing Insects
Affected Area: Insect that affects the entire plant.

Description: Root weevils are shiny black or brown and measure to 5-6 mm in length. These weevils tend to eat notches out of the leaves and eventually move down to the crowns and roots of the plant. The damage to the crowns and roots is the more serious damage to the plant causing stunted growth, and eventually killing the entire plant.

Control: A few insecticides may be used to control root weevils.


Problem: Flower Thrips
Affected Area: Insect that affects the flowers and fruit of the p

Description: Flower thrips are very short yellow insects that are hard to detect. Up to ten thirps can attack one flower of a strawberry plant before any type of insecticide is needed. Thirps generally attack the flower and move to the fruit causing bronzing and hardness of the fruit.

Control: Control measures may include the application of one of various insecticides or choosing a variety that is less susceptible to flower thrips.


Problem: White Grubs
Affected Area: Minor insect

Description: Control measures may include preplant soil treatments with soil fumigants and insecticides.

Control: Pest


Problem: Leaf Rollers
Affected Area: Minor Insect

Description: Many natural parasites help control the leaf rollers to a low population.

Control: Pest


Problem: Strawberry Sap Beetle
Affected Area: Insect that attacks the fruit of the plant.

Description: Strawberry sap beetles are small and very thing with pale spots their bodies. These insects attack the fruit as it begins to ripen creating holes in the fruit and reproducing inside the fruit. It is difficult to detect because the insects make their holes at the bottom of the fruit and are rarely seen.

Control: Control of strawberry sap beetles is difficult to accomplish because of the restrictions of insecticide use just before harvest. But picking and destroying rotten and infested fruits will decrease the damage for the next crop and lower the population.


Problem: Slugs and Snails
Affected Area: Leaf

Description: Large portions of young plants missing.

Control: Slugs and snails are very susceptible to desiccation (drying) and require a moist, shady place to live. Cultural practices which promote a sunny, dry environment will discourage them. Avoid too-frequent waterings allowing soil surface to dry out between irrigations. Keep garden free of debris, boards, bricks, and stones where they hide. Hand picking these pests is very effective. Create ?traps? for hand picking by laying boards in the garden. Slugs and snails will congregate under them. Lift the boards each morning and collect the slugs and snails. Dispose of them completely as they will crawl back if tossed out of the garden and eggs inside dead pests can still hatch to produce more of these pests. Slug and snail bait containing metaldehyde can be placed near food plants as long as they do not contact edible portions of the crop. Most effective when moistened, but not water logged. Snail bait attracts slugs and snails from several feet away so bait stations are effective. Stations help protect birds, pets and other non-target animals which are also attracted to the bait. Place small piles of bit under a slightly propped up board or use container such as a cottage cheese or yogurt carton. Bury carton to the mouth of the container. Place small amount of commercial bait inside and moisten with apple juice, orange juice or water. Cut hole in lid to allow access and place lid on container. Containers may also hold beer or yeast water to attract slugs and snails in where they drown. Place bait stations wherever slugs and snails are active or around perimeter of garden.


Problem: Strawberry Root Weevil
Affected Area: Root

Description: Adults are 3/8 inch, grayish-black or brown/black beetles with short snouts, and elbowed antennae. Strawberry root weevil wings are fused and the insects do not fly. True to its name, the strawberry root weevil is most attracted to strawberries and can cause severe damage to them. Adults emerge from the soil during the night and feed on leaves of plants. Leaf damage is largely cosmetic. Beetle larvae live underground and feed on the roots. The larvae are plump, up to 1/2 inch long and lightly curved with brown heads and no legs. They cause the real damage as their root feeding can cause the plants to grow slowly, wilt, collapse, and die.

Control: Destroying old beds of strawberries can kill developing larvae. This is best done after the eggs are laid. Move new strawberry beds, using new plants, to other locations as far as possible away from the old beds. Keep the area cleaned up to avoid giving the adults a shelter. If the problem is serious, treat food plants with *Diazinon in midsummer and again one month later, or use a commercial bait such as *Morgro Pest pellets * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Leaf roller
Affected Area: Leaf

Description: Caterpillars which roll up or tie up leaves with their silk

Control: * Malathion or *Dipel * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Birds
Affected Area: Leaf

Description: Birds are fond of strawberries and consistently damage fruit flying in to pluck it or peck at it.

Control: Bird netting over plants.


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 wihch 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: 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.





Strawberries

Tips

Strawberries are related to roses.

 

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