Both plant bugs and drought stress can cause poor fruit retention. However, large scars were noted at the aborted fruiting sites, indicating the problem was not due to plant bugs. Plant bugs cause abortion of pinhead squares, which leaves small scars. Large scars indicate boll rather than square abortion. In fields where the problem was detected early, small and abnormally shaped bolls could be found on the ground.
Drought stress can cause abortion of small bolls on heavily fruited cotton.
However, abortion of small bolls was observed in some fields that had just begun blooming and were not under moisture stress. Roundup-induced fruit abortion is a result of poor pollination, although the exact cause of the poor pollination is unknown. Such bolls had low seed counts in many locks. An excessive amount of cavitation was also observed in some growers' fields planted to DPL 5409, DPL 458, DPL 655, DPL 5415RR, DPL 5690RR and DPL 90RR in 1998 and 1999. Cavitated fruit turn brown and dry up, but they hang on the plant for a few weeks rather than shed.