Dog days of summer bring out plant pests

Western flower thrips, spider mites, potato leafhoppers and tarnished plant bugs are just a few of the insect pests that growers are encountering during the hot weather of summer. Univ. of Conn. extension horticulture and greenhouse IPM specialist Leanne Pundt said thrips populations tend to increase as more plants are flowering. During summer months as grass or nearby hay fields are mowed, thrips often enter greenhouses through vents and open roofs. Thrips may migrate to yellow flowering weeds so good weed control can help reduce populations.

Growers are also being advised to monitor ornamental cabbage and kale plants for imported cabbageworm. Univ. of Md. extension personnel said growers should also look for cross-striped cabbage worm and cabbage looper on these crops. Pansy growers should be looking for the caterpillars of variegated fritillaries on their plants.

Diseases that have been showing up on summer crops include Southern blight on begonia caused by Sclerotium rolfsii. This disease is particularly difficult to control in the landscape because the fungus remains viable for several years.

Alternaria has been found on cut sunflowers appearing as brown to black spots on the lower leaves.