Stinkbug Damage Common in Tomatoes This Year

Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu

This has been one of the worse years for stink bug damage in tomatoes that I have seen in a while. Just about every field I walk into has at least some damage while others have severe damage (>35% tomatoes not marketable). Cloudy spot of tomato fruit is caused by the feeding of various species of stink bug (SB). On green fruit the damage appears as whitish areas with indistinct borders (Fig. 1). Individual spots may be ¹/₁₆ – ¹⁄₂ inch in diameter; or, the spots may merge and encompass a large area of the fruit surface. On ripe fruit the spots are golden yellow (Fig. 1). Peeling back the skin shows these areas as white shiny, spongy masses of tissue (Fig.1). This damage is most common from late July or early August until the end of the season, concurring with the activity and feeding of stink bugs. SBs are often difficult to see and usually go unnoticed as they spend much of the day on the ground beneath tomato plants, which results in monitoring problems. Only a few are necessary to cause the appearance of cloudy spot on many tomato fruit. Brown marmorated stink bugs (Fig. 2) as well as leaf-footed (Fig. 3) and tarnished plant bugs also have been observed in larger than usual numbers in tomato fields. The brown marmorated SB may be responsible for some of the more severe feeding damage observed in some tomato fields. The leaf-footed and tarnished plant bugs usually do not do as much damage to fruit as the larger stink bugs. Feeding damage by the immatures of any of the stink bugs often appears as yellow “star-bursts” on red fruit (Fig. 4), which causes a very small shallow white spongy area under the star-burst (Fig. 5).

Stink bugs and tarnished plant bugs usually move into the edges of tomato fields and seldom are found in the interior of the fields, suggesting that spraying the edges of fields could be used as a control tactic. Stink bugs and especially the leaf-footed and tarnished plant bugs, tend to move into tomato fields when preferred hosts that are adjacent to the fields are disturbed or dry out.

This is an extremely difficult pest to monitor and control. There are no good methods of monitoring these pests. Traps do not work well except for just a few species of stink bug, visually scouting for them has proven to be unreliable and too time consuming. Usually SB damage is only a nuisance, but this year it has resulted in large losses in some fields. Growers who have had damage before from stinkbugs may want to examine the edges of their fields carefully starting in mid-June for tomatoes with cloudy spot. If it is a dry year as this year has been, it would probably be best to start in early June checking for damage. There are some acceptable chemical choices for stink bug control. Pyrethroids (Warrior II, Baythroid XL, Mustang MAX), Venom, Leverage, Voliam Xpress, or Tombstone can be used to reduce damage. It should be understood that none of the chemicals will give complete control, but will reduce damage significantly compared with no chemical usage.