Cloudy spot of tomato fruit is caused
by the feeding punctures of stink bugs. The symptoms are believed to be
due to a toxin injected into the fruit when stink bugs (Pentatomids
spp) feed on the fruit. This is one of the most common problems found
in home gardens in Illinois.
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Symptoms
On the green fruit, the symptoms appear as whitish areas
with indistinct borders. Isolated spots may be from 1/16 to over 1⁄2
inch in diameter; or, the spots may emerge and involve a large portion
of the fruit surface. On ripe fruit the spots are light yellow (Figure
1). Peeling back the skin shows the discolored areas as superficial, shiny,
somewhat spongy masses of tissue composed of silvery white cells. The
cloudy spots may be cut out by the processor if top-quality, canned, whole
tomatoes are desired.
The condition is most common from late July or early
August until the end of the season, coinciding with the activity and feeding
of the stink bugs (Figure 2). These insects may be so few in number that
they go unnoticed. However, only a few are necessary to cause the appearance
of cloudy spots on most tomato fruit in a home garden. The problem is
most prevalent where weeds have not been adequately controlled favoring
high populations of stink bugs.
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Figure
1. Cloudy spot on ripe fruit - note light yellow spots on fruit. (Courtesy
Kansas State University)
Figure
2. Stink bug feeding on green leaf.
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