Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu
This has been a bad year for stink bug damage in tomatoes. Just about every field I walk into has at least some damage, while others have moderate to heavy damage (>20% 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 and green stink bugs have been observed in larger than usual numbers in tomato fields. The brown marmorated stink bug does not appear to be causing much damage in vegetables so far this year compared with previous seasons. Feeding damage by the immatures of any of the stink bugs often appears as yellow “star-bursts” on red fruit (Fig. 2), which causes a very small shallow white spongy area under the star-burst (Fig 3).
Figure 1. Severe stink bug feeding on green and red fruit. Outer skin peeled back showing spongy white area.
Stinkbugs are extremely difficult pests to monitor and control. There are no good methods for monitoring these pests. Traps do not work well, 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 moderate 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. There are some acceptable chemical choices for stink bug control. Pyrethroids (Warrior II, Baythroid XL, Hero EC, Tombstone and Mustang MAX), Venom or Scorpion or Lannate LV can be used to reduce damage. It should be understood that none of the chemicals will give complete control, but will reduce damage compared with no chemical usage.
Figure 2. Star-burst pattern of immature stink bug feeding
Figure 3. Spongy white area under star-burst feeding stink bug feeding.