New research into aphid control. Tom Pope & Juliane Graham, Harper Adams University

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1 New research into aphid control Tom Pope & Juliane Graham, Harper Adams University

2 Aphid pests of strawberry Strawberry aphid (Chaetosiphon fragaefolii) Influential Points Shallot aphid (Myzus ascalonicus) Influential Points Melon and cotton aphid (Aphis gossypii) Influential Points Glasshouse-potato aphid (Aulacorthum solani) Potato aphid (Macrosiphum euphorbiae)

3 New research into aphid control Completed as part of AHDB Horticulture Project SF Improving integrated pest management in strawberry Follows on from AHDB Horticulture Project SF 140, which indicated potential importance of spray coverage Recent withdrawals of chlorpyrifos and pirimicarb Work completed in two parts: Experiment 1 Detailed polytunnel based study Experiment 2 Leaf bioassays

4 Treatments tested in polytunnel and Treatment No. Product Name leaf assays Active Ingredient 1 Hallmark lambda-cyhalothrin 2 Hallmark + Silwet lambda-cyhalothrin + trisiloxane ethoxylate 3 Calypso thiacloprid 4 Calypso + Silwet thiacloprid + trisiloxane ethoxylate 5 Chess pymetrozine 6 Chess + Silwet pymetrozine + Trisiloxane ethoxylate 7 Silwet trisiloxane ethoxylate 8 Water control water 9 Untreated control * - * Leaf dip only

5 Detailed polytunnel based study Overwintered strawberry plants infested with potato aphid identified by Berry Gardens agronomists Aphid infested plants (var. Driscolls Diamond) collected late March and potted into 5 l pots Plants maintained in ventilated polytunnel at Harper Adams Aphid numbers reached approx. 20/plant by end of April

6 Detailed polytunnel based study Application method: Air assisted knapsack sprayer Applied sprays at 1000 l/ha Each plant received 25 ml of sprayate Experimental Design: Randomised block design 8 treatments each with 5 replicates Plants separated using horticultural fleece plot dividers

7 Detailed polytunnel based study Timetable: Activity Date Pre-treatment count 2 nd May 2016 Insecticide application 3 rd May Day after treatment count 4 th May Days after treatment count 6 th May Days after treatment count 11 th May Days after treatment count 18 th May 2016 Assessed aphid numbers on: Crown, leaf petiole and leaf (upper and lower surface) Flower stem, bracts and petals (as these developed)

8 Detailed polytunnel based study aphid numbers Treatment application

9 Results aphid position on plant Crowns only Petioles only Moderate numbers Lower leaf surfaces only Moderate numbers Upper leaf surfaces only High numbers Low numbers

10 Results aphid position on plant Bracts only Flower stems only Moderate numbers Petals only High numbers Low numbers

11 Leaf assays Method used based on Insecticide Resistance Action Committee (IRAC) test method Expanded leaves (var. Elsanta) collected and: sprayed to run-off, allowed to dry before being or infested with 20 immature aphids infested with 20 immature aphids (24 hours) then sprayed to run-off then allowed to dry Leaves maintained in ventilated Petri dishes at 20 C and 60% relative humidity Aphids assessed 1, 3 and 6 days after treatment application

12 Leaf assays Treatment No. Product Name Aphids placed onto sprayed leaves 1 Hallmark * * 2 Hallmark + Silwet * * 3 Calypso * 4 Calypso + Silwet * 5 Chess 6 Chess + Silwet 7 Silwet 8 Water control 9 Untreated control <50% dead after 6 days 50-75% dead after 6 days >75% dead after 6 days *100% kill within 24 hours Aphids directly sprayed

13 Conclusions Detailed polytunnel experiment: Hallmark effectively controlled potato aphid on overwintered strawberry plants Use of the wetter Silwet did not improve control Calypso and Chess did not control potato aphid Leaf assays: Hallmark and Calypso effective against potato aphid in both assays Chess and Silwet more effective as controls when aphids directly sprayed

14 Thank you!