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Market Diseases of Apples, Pears, and Quinces
Pansy Spot |
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Frankliniella tritici Fitch
Pansy spot is of economic importance only on apples grown in western states. Ordinarily thrips are controlled in well-sprayed orchards. In certain years, however, when conditions favor increased thrip populations, some fruits may be blemished and their value reduced. Most years, however, pansy spot is of minor importance. Pansy spot, a lobed spot suggesting the shape of a pansy flower, results from the egg-laying activities of flower thrips (Frankliniella tritici Fitch) on apple fruits. The spots, often exceeding 1/2 inch across, are white or greenish on green or yellow apple varieties (see photo). Occasionally on Golden Delicious, dark red spots are found. On red varieties such as McIntosh and Delicious, the spots are light red or pink. A greenish-brown corky spot, seldom more than 1/8 inch in diameter, in the center of the lesion marks the site of the puncture made by the female thrip during the egg-laying process. The spots are conspicuous on immature fruits, and can become serious defects on some varieties at harvest. On McIntosh the normal red color of the fruits fails to develop in the affected areas. On Delicious, however, the development of the natural pigment is not greatly inhibited and the spots become less conspicuous on mature fruits. The spots do not enlarge or change while the fruits are in storage. Orchard sprays are used to control thrips. The recommendations of the State extension service or experiment station should be followed in establishing spray programs for this purpose. |
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