Agronomic Spotlight

Several species of aphids can be found on pepper plants, but not all of them cause significant problems. The green peach aphid causes the most problems on peppers.^1,2 They are found mostly on the undersides of leaves, on terminal buds, and around flowers. Damage is usually greatest during periods of warm, dry weather, and populations typically decline after a heavy rainfall.

Plant death from aphid feeding is rare, but feeding can result in the shedding of blossoms and curling and stunting of new growth. Aphids produce a sticky honeydew that is difficult to remove from the fruit. The honeydew also allows sooty mold fungi to grow, covering leaves and fruit with dark mold growth that reduces photosynthesis and lowers fruit quality.^2,3,4 Aphids also vector several important viruses on pepper, including Cucumber mosaic virus, Potato virus Y, Tobacco etch virus, and Beet western yellows virus.⁴

Sanitation through the destruction of crop debris quickly after harvest and controlling weeds in and around the field helps keep populations low and eliminate virus hosts.^1,4,5 If infestations become significant, insecticide applications may be warranted. However, the use of insecticides can result in an increase in aphid populations because they lower populations of natural enemies in the planting.^2,3

Several insecticides are available for controlling or suppressing aphids (Table 1), and they vary in how they can be applied (soil vs. foliar), their pre-harvest intervals (PHI) and restricted entry interval (REI), and other characteristics.

Coverage by the insecticide needs to include the undersides of leaves where the aphids typically feed.³ The development of insecticide resistant populations of aphids is a concern, so it is best to mix or alternate applications of insecticides belonging to different mode of action groups.

Stink bugs are shield-shaped insects, 1/2 to 3/4 inches long, that can be significant pests on peppers. Green, brown, and more recently brown marmorated stink bugs (BMSB) are the most common stink bugs on peppers.³ They feed on a wide range of hosts, with the BMSB causing damage on hosts ranging from apples and blackberries to corn and soybeans.⁶ These insects overwinter as adults in ditch banks, in fence rows, and in wooded areas. They are usually most damaging during dry periods when temperatures rise above 70°F, and populations tend to decline during periods of heavy rainfall.³

Symptoms of stink bug feeding include malformation of developing fruit, small dimpled green areas on the fruit, or “cloudy spots” on the fruit where the cells below the surface shrivel, and the area becomes white and spongy.

Scout for stink bug adults on the edges of the field, especially near wooded areas, and begin treating when adults are detected. Control weeds in and around the field to lower stink bug populations. The number of available insecticides that provide good control of stink bugs is somewhat limited, but the occurrence of resistant populations is not common.¹

Several species of whiteflies can be found on peppers, but only silverleaf whiteflies and greenhouse whiteflies cause significant damage. These insects are very small (3/50 inch long), yellowish in color with white wings. They have a wide host range, including crops such as melons, cole crops, and cotton. They are found mostly on the undersides of leaves and readily fly when disturbed. Whiteflies suck large amounts of sap from leaves and cover them with honeydew that promotes the growth of sooty mold fungi. High populations stunt plant growth and reduce yields.⁵

The presence of whiteflies can be inconsistent from season to season. Using practices that conserve natural enemies, quickly destroying crop residues after harvest, and managing host weed species in and around fields can all help to keep populations low. Monitor field margins for whiteflies, especially when nearby host plants are declining. Insecticide applications should cover the undersides of leaves to be most effective.