David Owens, Extension Entomologist, owensd@udel.edu
Tarnished plant bug were observed in large numbers at plots in Georgetown this past week. Tarnished plant bug feed on flowers and developing fruit, causing cat facing, deformity, and button berries. The nymphs are small and lime green, adults are mottled brown and a little bit smaller than a pencil eraser. Scout for tarnished plant bug by shaking 30 flower trusses or clusters (6 groups of 5 across the field) on a dark sheet or on the black plastic where the nymphs will be more easily seen. Count the number of infested flower clusters (not number of nymphs). A variation on the sampling method is to first sample 15 flower clusters. If 0 clusters are infested, you do not need to spray but if 3 or more are infested, control is justified. If between 0-3, check 5 more flower clusters. The complete sequence can be found here: https://ag.umass.edu/fruit/fact-sheets/strawberry-ipm-tarnished-plant-bug. There are a plethora of materials that can be used for plant bugs, including Malathion, Brigade, Danitol, Brigadier, Assail, Cormoran, Transform, Closer, Apta, and Beleaf. The best OMRI approved material is Azera, a mixture of azadirachtin and pyrethrin.
In addition to tarnished plant bug, sample for spider mites if you haven’t already done so. Thresholds during the flowering and fruiting stage are 15 – 20 mites per leaflet. Take 10 mid-canopy leaflets (not the full leaf) per acre and count mites. If you count between 150 and 200 mites, a treatment is generally justified.