Work was initiated in 1985 to determine if nitrogen stress imposed by none or excessive preplant nitrogen would cause small squares to shed. Abscissing squares approximately 3 mm in diameter from plant terminal and limb occurring at the sixth main stem node from the terminal were collected throughout the fruiting season from plants receiving 0, 84, and 168 kg/ha preplant nitrogen. Squares were sectioned, observed through a 30X scope, and classified as insect-induced or physiological sheds. test plots had received the above of preplant nitrogen annually since 1973. The experimental design was a randomized complete block with 9 replications of 6-row plots, 21 x 0.97 m. The test site was Calloway silt loan, a fine-silty, mixed thermic, Fraguidalf and was furrow irrigated.

All shed squares examined prior to the initiation of booming within each nitrogen treatment had been damaged by plant bugs. From first bloom through the forty-second day of blooming, a near linear increase from 0 to approximately 75% of the examined shed squares had not been damaged by insects, i. e. were physiological sheds, in the 84 and 168 kg N/ha treatments. The percentage of sheds that were physiological rather than insect-induced was significantly higher in the 0 N treatment for the first 14 days of blooming but was not significantly different from the 84 and 168 kg/ha rates thereafter. The percentage of examined squares that shed because of physiological reasons did not exceed the percentage that had been damaged by plant bugs until the upper most white bloom at the first position average < 7 nodes plant terminals.