strawberry weevil grubs - Ask Extension
what is the most effective way to eliminate strawberry weevil grubs. Is there a granular product to put down to kill them. I have a patch about 4' x 6...
Knowledgebase
strawberry weevil grubs #171551
Asked March 25, 2014, 3:55 PM EDT
what is the most effective way to eliminate strawberry weevil grubs. Is there a granular product to put down to kill them. I have a patch about 4' x 60'
Linn County Oregon
Expert Response
Hi There,
Unfortunately, a granular product would not be the most effective approach to control root weevils in strawberries ~ because of the behavior of the insects is such that you need to catch the adults when (at night) and where (on the foliage) they're feeding. Below my suggestions for chemical controls, I've pasted text from the PNW Insect Management Handbook (http://pnwhandbooks.org/insect/small-fruit/strawberry/strawberry-root-weevil) that describes the biology of the pests a bit more ~ and how and when home gardeners should scout for this pest. The trick is to catch the adults (which are exposed to any control measure you might throw at them) during the narrow window of time from April through early June ~ when adults have emerged from pupation, but before they lay eggs and 'seed' your strawberries with the next generation of root feeders.
The three chemical controls given are malathion, carbaryl and pyrethroids. I've gone through a database of home use labels and have found the following products that have strawberries listed on the label.
All products will be most effective if used when adults are actively feeding (at night . . . and you'll have to scout for adults as suggested, or else be cued in to new 'notching' on your strawberry leaves to know whether or not it is the right time to manage the pests).
Bonide Insect Control Vegetable Fruit and Flower Concentrate (2.5% permethrin). This is an organic product. Please note that the label requires you wait at least 14 days between a pesticide application and strawberry harvest.
Sevin Ready to Use (0.126% carbaryl)). Please note that the label requires you wait at least 7 days until between a pesticide application and strawberry harvest.
Malathion is your third chemical control option, but this pesticide has more negative environmental and human health effects than the carbaryl and pyrethrin options.
Nematodes are a good biological control option. Whereas the chemical controls will target the adults (and your window of time is April through June), nematodes target the larvae. So, if you miss the window of time to control adult beetles, you can use nematodes to control the larvae from June to September. Since the nematodes are a living, biological control, you need to make sure that conditions are right for their survival (i.e. don't apply them with pesticides; make sure soil is most; temperatures should be above 55 degrees F and less than 90 degrees F, etc.). See link below for more information.
Good luck!
http://pnwhandbooks.org/insect/ipm/entomopathogenic-nematodes
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- See more at: http://pnwhandbooks.org/insect/small-fruit/strawberry/strawberry-root-weevil#sthash.dLLqjycR.dpuf
Unfortunately, a granular product would not be the most effective approach to control root weevils in strawberries ~ because of the behavior of the insects is such that you need to catch the adults when (at night) and where (on the foliage) they're feeding. Below my suggestions for chemical controls, I've pasted text from the PNW Insect Management Handbook (http://pnwhandbooks.org/insect/small-fruit/strawberry/strawberry-root-weevil) that describes the biology of the pests a bit more ~ and how and when home gardeners should scout for this pest. The trick is to catch the adults (which are exposed to any control measure you might throw at them) during the narrow window of time from April through early June ~ when adults have emerged from pupation, but before they lay eggs and 'seed' your strawberries with the next generation of root feeders.
The three chemical controls given are malathion, carbaryl and pyrethroids. I've gone through a database of home use labels and have found the following products that have strawberries listed on the label.
All products will be most effective if used when adults are actively feeding (at night . . . and you'll have to scout for adults as suggested, or else be cued in to new 'notching' on your strawberry leaves to know whether or not it is the right time to manage the pests).
Bonide Insect Control Vegetable Fruit and Flower Concentrate (2.5% permethrin). This is an organic product. Please note that the label requires you wait at least 14 days between a pesticide application and strawberry harvest.
Sevin Ready to Use (0.126% carbaryl)). Please note that the label requires you wait at least 7 days until between a pesticide application and strawberry harvest.
Malathion is your third chemical control option, but this pesticide has more negative environmental and human health effects than the carbaryl and pyrethrin options.
Nematodes are a good biological control option. Whereas the chemical controls will target the adults (and your window of time is April through June), nematodes target the larvae. So, if you miss the window of time to control adult beetles, you can use nematodes to control the larvae from June to September. Since the nematodes are a living, biological control, you need to make sure that conditions are right for their survival (i.e. don't apply them with pesticides; make sure soil is most; temperatures should be above 55 degrees F and less than 90 degrees F, etc.). See link below for more information.
Good luck!
http://pnwhandbooks.org/insect/ipm/entomopathogenic-nematodes
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Strawberry-Root weevil
Strawberry root weevil
Otiorhynchus ovatus Linnaeus
Showing damage on leaves
"Rough strawberry root" weevil
Otiorhynchus ruqosostriatus Goetze
Adult
Black vine weevil
Otiorhynchus sulcatus Fabricius
Immature on host
Includes
Black vine weevil (Otiorhynchus sulcatus)
Rough strawberry root weevil (O. rugosostriatus)
Strawberry root weevil (O. ovatus) Pest description and crop damage Black vine weevil (BVW) is probably the most common weevil to infest strawberries, but the strawberry root weevil (SRW) and rough strawberry root weevil (RSRW) are also pests. Adult weevils are 8-12 mm long, depending on the species. Adults are reddish brown to black; the BVW is larger and darker than the other species. Larvae of all species are quite similar in appearance and habits: they are C-shaped, legless, white with tan heads, and up to 12 mm long. Adult weevil feeding causes a characteristic notching in the leaves of strawberries and other host plants. This feeding damage is relatively minor and causes little damage to the plants. The real damage is done by the larvae, which feed through the winter and spring on the root systems of host plants. Larvae feeding on roots can cause stunting and poor yields. With severe infestations, plants may die. Biology and life history Weevils overwinter as larvae in the soil. Feeding may occur throughout mild winters. In April-June, larvae pupate, and adult emergence occurs during this time. Adults are night feeders that remain in the soil or in organic material at the base of the plant during the day, then climb up to feed on leaves at night. Adult weevils cannot fly, but walk or are carried from one location to another on plant material or equipment. Also, all adults are females capable of laying eggs. Adults are slow moving and should not be confused with swifter predacious ground beetles. Eggs are laid in clusters in or on the soil from June to September. The eggs hatch and the larvae immediately wriggle through the soil to begin feeding. There is one generation per year. Scouting and thresholds Inspect leaves for notching from adult feeding in early summer. Controls should be undertaken soon after adult feeding is observed, but before egg laying occurs, generally about four weeks. Presence of adults can be confirmed by night inspection of foliage on warm, still evenings. Or, look for adults in the day by looking through plant debris at the base of the plant. Laying a small piece of cardboard next to the strawberry plant will provide a refuge that can be checked easily in the early morning.
Rough strawberry root weevil (O. rugosostriatus)
Strawberry root weevil (O. ovatus) Pest description and crop damage Black vine weevil (BVW) is probably the most common weevil to infest strawberries, but the strawberry root weevil (SRW) and rough strawberry root weevil (RSRW) are also pests. Adult weevils are 8-12 mm long, depending on the species. Adults are reddish brown to black; the BVW is larger and darker than the other species. Larvae of all species are quite similar in appearance and habits: they are C-shaped, legless, white with tan heads, and up to 12 mm long. Adult weevil feeding causes a characteristic notching in the leaves of strawberries and other host plants. This feeding damage is relatively minor and causes little damage to the plants. The real damage is done by the larvae, which feed through the winter and spring on the root systems of host plants. Larvae feeding on roots can cause stunting and poor yields. With severe infestations, plants may die. Biology and life history Weevils overwinter as larvae in the soil. Feeding may occur throughout mild winters. In April-June, larvae pupate, and adult emergence occurs during this time. Adults are night feeders that remain in the soil or in organic material at the base of the plant during the day, then climb up to feed on leaves at night. Adult weevils cannot fly, but walk or are carried from one location to another on plant material or equipment. Also, all adults are females capable of laying eggs. Adults are slow moving and should not be confused with swifter predacious ground beetles. Eggs are laid in clusters in or on the soil from June to September. The eggs hatch and the larvae immediately wriggle through the soil to begin feeding. There is one generation per year. Scouting and thresholds Inspect leaves for notching from adult feeding in early summer. Controls should be undertaken soon after adult feeding is observed, but before egg laying occurs, generally about four weeks. Presence of adults can be confirmed by night inspection of foliage on warm, still evenings. Or, look for adults in the day by looking through plant debris at the base of the plant. Laying a small piece of cardboard next to the strawberry plant will provide a refuge that can be checked easily in the early morning.
