Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu
There have been reports of stinkbug damage in tomatoes in Maryland for the last couple of weeks. Stinkbug feeding damage is called cloudy spot in tomato fruit (Fig. 1). It occurs when the adult or immature stinkbug puts its needle-like mouth part into the fruit and removes material from a large number of cells. On green fruit the damage appears as whitish areas with a black dot in the center and indistinct borders (Fig. 2) on ripe fruit the spots are golden yellow (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 (Fig. 2). Peeling back the skin shows these areas as white shiny, spongy masses of tissue (Fig. 3). This damage is usually most common from mid-July until the end of the season. The Green and Brown as well as the Brown Marmorated stinkbugs are often difficult to see and usually go unnoticed as they spend much of the day deep inside tomato plants, any disturbance and the stinkbugs will drop to the ground and move under the plastic, which results in monitoring difficulties. Only a few are necessary to cause the appearance of cloudy spot on many tomato fruit. Although stinkbug damage has been observed in slightly greater than usual amounts in tomato fields this year, observations of stinkbugs have been much less numerous.
Stinkbugs are difficult pests to control. As alluded to earlier there are no good methods for monitoring these pests. Usually stinkbug damage is only a nuisance, but in some years, it has resulted in moderate losses in particular fields. Growers should examine the edges of their fields carefully for tomato fruit with cloudy spot. There are some acceptable chemical choices for stink bug control. Pyrethroids (Warrior II, Hero EC, Tombstone and Mustang Maxx) or Venom or Scorpion can be used to reduce damage. Sprays should be directed towards the center of the plant with high pressure and a high gallonage (50-100 gal/a). If harvest has started there are neonics and pyrethroids that have very short PHIs – check your Mid-Atlantic Commercial Vegetable Production Recommendations guide. It should be understood that none of the chemicals will give complete control but will reduce damage compared with no chemical usage. Organic growers can try Entrust or Azera or Pyganic for control of nymphs, but these chemicals will not control adults.
Figure 1. Stinkbug injury to tomato fruit
Figure 2. In the center of each cloudy spot is a tiny black dot (arrows) where stinkbug mouthparts penetrated into the tomato
Figure 3. Stinkbug feeding causing cloudy spot (arrows) on tomato fruit with skin peeled back