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Insects - 209-Insect Control Guide for Wild Blueberries

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209-Insect Control Guide for Wild Blueberries

Fact Sheet No. 209, UMaine Extension No. 2001

Prepared by David E. Yarborough, Extension Blueberry Specialist, Frank Drummond, Professor of Insect Ecology, School of Biology and Ecology, and Judith A. Collins, School of Biology and Ecology. The University of Maine, Orono, ME 04469. Revised February 2014.

NOTICE: It is unlawful to use any pesticide for other than the registered use. Read and follow the label on the product container.The user assumes all responsibility for use inconsistent with the label.

This fact sheet is to be used only during 2014. Use in subsequent years may lead to improper and illegal use of pesticides. When this guide is outdated, please request an updated version from your Extension office.

WARNING! Pesticides are potentially hazardous. Handle carefully! Read and follow all directions and precautions on labels. Store in original labeled containers out of reach of children, pets and livestock. Dispose of empty containers at once, in a safe manner and place. Do not contaminate forage, streams, ponds or groundwater recharge areas.

Groundwater is a major natural resource. Pesticides have been detected in the groundwater of all states. A sound application program including site-specific selection, adherence to label directions, sprayer calibration mixing accuracy, spill and back siphon prevention, proper waste disposal, integrated pest management and judicious pesticide use can prevent groundwater contamination.

Trade names are used for identification. No product endorsement is implied, nor is discrimination intended against similar materials. Cooperative Extension makes no warranty or guarantee of any kind concerning the use of these products.

Blueberry Spanworm

Begin to monitor for spanworm larvae in early spring as the buds break and plants emerge by sweeping with a 12-inch diameter sweep net. Spray with an insecticide or biocontrol when larval counts on fruit-bearing plants average over 10 per 10 sweeps. The action threshold should be lowered to 3 or more larvae per 10 sweeps on vegetative year fields. Repeat treatment if necessary. More information may be found in the Wild Blueberry Fact Sheet No. 197 (UMaine Extension No. 2371), Blueberry Spanworm.

Blueberry Flea Beetle

An action threshold of 50 insects per 10 sweeps has been established for either larvae or adults. Examine fields in early spring for larvae and from mid-June to early July for foliar feeding by adults. Spray with an insecticide or biocontrol as needed. More information can be found in Wild Blueberry Fact Sheet No. 200 (UMaine Extension No. 2372), Blueberry Flea Beetle.

Thrips

When leaf curling occurs in a fruit bearing year, stake out infested area. Consider pruning as a control; see the cultural techniques section. The following spring, apply insecticide to the staked area before curling reoccurs. Make first application when leaves are 1/4 inch to 1/2 inch long. Repeat when 1/2 inch to 1 inch. These timings are critical. Yellow sticky cards may be used to monitor for blueberry thrips for more efficient timing of applications. Refer to Wild Blueberry Fact Sheet No. 204 (UMaine Extension No. 2275), Integrated Crop Management Field Scouting: Guide for Lowbush Blueberries and Wild Blueberry Fact Sheet No. 202 (UMaine Extension No. 2373), Blueberry Thrips.

Blueberry Maggot

Monitoring for the presence of the blueberry fruit fly will indicate necessity for control based on trap capture threshold and, if needed, to ensure proper timing of insecticide applications. Cooperative Extension Fact Sheet No. 201 (UMaine Extension No. 5030), Monitoring for the Blueberry Maggot, outlines ways to monitor fields for the blueberry fruit fly and discusses perimeter treatments that greatly reduce the portion of the field that needs to be treated.

Never apply insecticides when less than three to five percent of berries have ripened and turned blue. This is usually early July in most regions of Maine. Repeat applications, if necessary, depending on trap capture results.

Spotted-Wing Drosophila

The Spotted-Wing Drosophila (SWD) is an invasive non-native small vinegar fly with the potential to cause considerable fruit loss of wild blueberries especially at the end of the harvest season. It was first detected in Maine in 2011. Unlike most other vinegar flies that require damaged fruit to attack, SWD causes damage when the female flies cut a slit and lay eggs in healthy fruit. Monitoring for the presence of the SWD requires a different trap, placement and timing than our native blueberry maggot fly. See Extension Fact Sheet: Spotted-Wing Drosophila Traps at http://umaine.edu/blueberries/factsheets/insects/spotted-wing-drosophila-traps/

Apply insecticides at first capture usually in mid-August in most regions of Maine. Repeat applications, if necessary, depending on trap capture results. In order to prevent development of resistance rotate different classes (see recommendation table for insecticide class).

All publications may be found on the web at http://extension.umaine.edu/blueberries/factsheets/

Cultural Techniques to Reduce Insect Infestation

More information may be found in Wild Blueberry Fact Sheet No. 253, Cultural Management for Insects
and Diseases in Wild Blueberries.

Insects Method Comments
Blueberry Maggot Harvesting Harvesting techniques that reduce fruit loss can minimize the number of infected fruit left on the plants and on the ground.
Management Keep isolated fields in same cycle.
Winnower cleanup Compost, burn or dispose of winnower refuse.
Flea Beetle, Sawfly, Spanworm Fire pruning Blueberry litter must be ignited.
Thrips Fire pruning Burn curled stems as soon as extensive curling occurs in early spring, but not later than June 1 in a nonbearing crop or reduction in next year’s fruit buds will occur.

 

Toxicity Rating of Blueberry Insecticides

L-Low VL-Very Low M-Medium H-High VH- Very High N-None-Slight

Insecticide Oral Dermal Mammal Fish Bird Bee

Environmental
Persistence

Admire Montana* (imidacloprid)
M
L
M
M
H
VH*
M
Assail (acetamiprid)
L
L
L
VL
L
L
L
Asana (esfenvalerate)
M
L
M
H
M
H
M
AzaGuard (neem, azadirachtin)
N
N
N
L
L
L
Botanigard (Beauveria bassiana)
N
N
N
N
N
VL
VL
BT (Bacillus thuringiensis)
VL
VL
VL
VL
VL
VL
VL
Confirm (tebufenozide)
L
L
L
M
L
VL
L
Cythion Malathion (malathion)
VL
VL
L
L
VL
H
VL
Danitol (fenpropathrin)
M
L
M
VH
L
VH
M
Delegate (spinetoram)
VL
VL
VL
M
L
H*
L
Diazinon
M
L
M
H
VH
H
M
Entrust, GF-120 NF (spinosad)
VL
L
L
M
N
H
L
Imidan (phosmet)
M
VL
M
H
M
H*
M
Intrepid (methoxyfenozide)
L
L
L
M
L
L
L
Sevin (carbaryl)
L
VL
L
M
VL
H
L-M
Mustang Max EC (zeta-cypermethrin)
H
M
H
H
NA
H
M

Most Information on toxicity ratings for older insecticides is adapted from Introduction to Pest Management,1982, by Metcalf and Luckmann.

* Highly toxic to bees if they are directly sprayed or come in contact before chemical is dried on the foliage, once dry toxicity is very low. Use Admire for blueberry thrips control prior to stem emergence in the pruned year only. Do not use Admire prior to or during bloom in fruit-bearing fields. Imidacloprid is highly toxic to bees if used as a foliar treatment during flowering and is toxic to birds feeding on treated seeds.

 

Chemical Insect Control Methods for Wild Blueberries

Apply insecticides when monitoring indicates insect populations have reached threshold levels. See
Wild Blueberry Fact Sheet No. 204 Integrated Crop Management Field Scouting Guide for Wild Blueberries for details.

Insect Material Rate (Amount of product/acre) Comments
Blueberry Maggot Malathion 5E (malathion) 1 pt. Apply at 10 day intervals. Reentry 12 hours, apply up to 1 day to harvest.
Malathion 8F 1.5 to 2.5 pts. Potential for phytoxicity at lower gallons/acre.
Imidan 70 WP (phosmet) 1.3 lb. Apply at 7-10 day intervals.Aerial ULV 2 gal/acre water.

Reentry 3 days, 3 days to harvest. Limit 5 1/8 lb/season.

Admire Prosystemic Protectant 4.6 F (imidacloprid) 2.1 to 2.8 oz. 3 days to harvest.

NOTE: Current research in the field suggests that there is little direct effect on bee survival at the colony level, but there is laboratory evidence that imidacloprid can enhance bee mortality due to interactions with other insecticides and fungicides. We will follow future research in this area and may change our recommendation if negative impacts on hives are demonstrated.

Montana 2F; 4F (imidacloprid) 2F – 4.8 to 6.4 oz;

4F – 2.4 to 3.2 oz.

3 days to harvest.

NOTE: See above.

GF-120 NF Naturalyte Fruit Fly Bait
(spinosad)
See label for specific rate information Organic. Specialized application equipment is required.
Asana XL (esfenvalerate) 9.6 oz. 14 days to harvest.
Sevin 4 XLR Plus (carbaryl) 2 qts.

Repeat as necessary up to 5 times but do not apply more than once every 7 days. 7 days to harvest.

OBSERVE BEE CAUTION.

Danitol 2.4 EC (fenpropathrin) 10 2/3 to 16 oz. No more than 2 applications per season not more often than every 14 days. 3 days to harvest; Re-entry -24 hrs.
Delegate WG (spinetoram) 3 to 6 oz

Can be used for aerial application with 10 gpa water. No more than 6 application/yr, not less than 6 days apart. PHI – 3 days REI – 4 hours.

OBSERVE BEE CAUTION.

Assail 30 SG (acetamiprid) 5.3 oz.

No more than 5 applications/ yr, not less than 7 days apart, PHI – 1 day, REI – 12 hrs.

NOTE: Assail like Admire is a systemic insecticide and so caution needs to be used in regards to bees. We have found no deleterious effects on honey bees at the colony level. However, it should be noted that laboratory studies have suggested deleterious effects on honey bees when Assail interacts with some fungicides used in blueberry. This has not been tested in the field yet, but prudent use of Assail so as not to expose bees to Assail and Group 3 fungicides is suggested. We will follow future research in this area and may change recommendation if negative impacts on hives are demonstrated.
Mustang Max EC (zeta-cypermethrin) 4.0 oz. 1 day to harvest. Reentry – 12 hrs.
Exirel (Cyantraniliprole)

13.5 to 20.5 oz.

Do not exceed 62 oz.

Do not apply prior to or during bloom, do not apply when bees are foraging. Rotate with products with different modes of action; minimum interval between treatments is 5 days.
Spanworm Larvae Imidan 70 WP (phosmet) 1.3 lb. Should be used on larger instar larvae. Apply at 7-10 day intervals. Aerial ULV 2 gal/acre water. Reentry 3 days, 3 days to harvest. Limit 5 1/8 lb/season.

OBSERVE BEE CAUTION.

Intrepid 2F (methoxyfenozide) 10-16 oz. Do not apply more than 48 fl oz per acre or make more than 3 applications per calendar year.

7 days to harvest. Minimum re-treatment interval is 7 days.

Asana XL (esfenvalerate) 4.8 to 9.6 oz. 14 days to harvest. Do not apply within 7 days to pollination.
Assail 30 SG (acetamiprid) 5.3 oz. See notes on Assail under blueberry maggot.
Sevin 4XLR Plus (carbaryl) 2 qts. 7 days to harvest. OBSERVE BEE CAUTION. Flea beetle adults only.
Spanworn Larvae BIOCONTROL Entrust SC (spinosad) ORGANIC

Success (spinosad)

4 to 6 oz. TOXIC TO BEES UP TO 3 HOURS FOLLOWING TREATMENT.
Biobit, Dipel, Lepinox, Javelin
(Bacillus thuringiensis)
Several formulations registered Apply to small early instar larvae for best control. Larval death not immediate, but feeding quickly inhibited. May use when bees are present.
Flea Beetle Imidan 70 WP (phosmet) 1.3 lb. Apply at 7-10 day intervals. Aerial ULV 2 gal/acre water. Reentry 3 days, 3 days to harvest. Limit 5 1/8 lb/season. OBSERVE BEE CAUTION.
Delegate WG (spinetoram) 3 to 6 oz. See Delegate comments under blueberry maggot.
Assail 30 SG (acetamiprid) 5.3 oz. See Assail comments under blueberry maggot.
Flea Beetle BIOCONTROL Botanigard ES** (Beauveria bassiana) 1 qt. Apply at 7-10 day intervals in evening. Flea beetle larvae only. Be sure no fungicide residues are in spray tank. Do not apply within 1 day to harvest. Best results occur when applications are made in the evening since sunlight kills the Beauveria spores over time. May use when bees are present.
Entrust SC (spinosad) 4 to 6 oz. TOXIC TO BEES UP TO 3 HOURS FOLLOWING TREATMENT.
Strawberry Rootworm Adults Imidan 70 WP (phosmet) 1.3 lb. Apply at 7-10 day intervals. Aerial ULV 2 gal/acre water. Reentry 3 days, 3 days to harvest. Limit 5 1/8 lb/season. OBSERVE BEE CAUTION.
Delegate WG (spinetoram) 3 to 6 oz. See Delegate comments under blueberry maggot.
Assail 30 SG (acetamiprid) 5.3 oz. See Assail comments under blueberry maggot.
Strawberry Rootworm Adults BIOCONTROL Entrust SC (spinosad) 4 to 6 oz. TOXIC TO BEES UP TO 3 HOURS FOLLOWING TREATMENT.
Spotted-Wing Drosophila Very Effective
Brigade WSB (bifenthrin) 16 oz. Pyrethroid, 1 day to harvest.
Delegate WG (spinetoram) 3 to 6 oz. Spinosyn, 3 days to harvest.
Imidan 70 WP (phosmet) 1.3 lbs. Organophosphate, 3 days to harvest.
Mustang Max EC (zeta-cypermethrin) 4 oz. Pyrethroid, 1 day to harvest. Do not apply more than 24 fl. oz product per season. Do not make applications less than 7 days apart.
Effective
Malathion 8 F 1.5 pts. Organophosphate. Maximum of 2 applications. 1 day to harvest.
Entrust SC, 
Success (spinosad)
4 to 6 oz. Spinosyn. Approved Organic formulation Entrust. 3 days to harvest. Check on numbers of applications/season. See 24C Label.
Fair Effectiveness
Sevin (carbaryl) 1 to 2 oz. Organophosphate. 7 days to harvest.
Assail 30 SG (acetamiprid) Use label rates. Neonicotinoid. 1 day to harvest. Add 1 lb. sugar/acre in spray tank to enhance performance.
AzaGuard (neem) Use label rates. Effective under low to moderate SWD pressure. Once the SWD numbers build up, change to another compound.
Exirel
(cyantraniliprole)
13.5 to 20.5 oz.

Do not exceed 62 oz.

Do not apply prior to or during bloom, do not apply when bees are foraging. Rotate with products with different modes of action; minimum interval between treatments is 5 days.
Limited Effectiveness
Pyganic 1.4 EC (pyrethrum) 16 to 64 oz. Pyrethrum. 0.5 days to harvest.
Thrips Diazinon
(diazinon)
2 formulations registered Make 1st application when new emergent sprouts are 0.25 to 0.5 inch high, second application when sprouts are 0.5 to 1 inch high.
Malathion
(malathion)
Several formulations registered.
Admire Prosystemic Protectant 4.6F
(imidacloprid)
2.1 to 2.8 oz. for sprout application during emergence NOTE: Current research in the field suggests that there is little direct effect on bee survival at the colony level, but there is laboratory evidence that imidacloprid can enhance bee mortality due to interactions with other insecticides and fungicides. We will follow future research in this area and may change our recommendation if negative impacts on hives are demonstrated.
Montana 2F; 4F (imidacloprid) 2F – 4.8 to 6.4 oz; or 4F – 2.4 to 3.2 oz. for sprout application during emergence (see Diazinon application timing)

Follow ALL label directions.

  • Accurate identification of pests and monitoring to determine the best times to spray are critical for achieving effective, economical control.
  • Apply pesticides only when economic thresholds are exceeded, based on monitoring.
  • Use caution while loading spraying equipment with pesticides. Follow all safety precautions.
  • Use common sense when applying pesticides. DO NOT contaminate nearby lands, buildings, water bodies and roadsides. Keep domestic animals and children away from fields.
  • For detailed information on safe spray use, please refer to the Wild Blueberry Growers Guide.
  • Avoid aerial application of pesticides near buildings, public roads or water supplies or on windy days.
  • Reentry restrictions: never enter a sprayed area without protective clothing or until stated on label.
  • Be sure your sprayer is well cleaned and does not have any fungicide residue when using Botanigard since fungicide will kill the living spores.

Protecting Honey Bees from Insecticides

  • All pesticides are not equally hazardous to bees. Select the one that is least hazardous. Commonly used insecticides are listed in the chart according to their relative hazards.
  • Do not apply insecticides near honey bee hives.
  • Treat plants before (check persistence for each insecticide, for instance Phosmet is 7-10 day persistence) or after bloom, at night with low persistence insecticides, or when bees are not actively foraging in crop and pruned fields.

Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.

© 2014
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