No more stinky cotton!
Following the eradication of the cotton boll weevil in the late 1990s cotton growers began to notice an influx of a new pest, stink bugs. Stink bugs feed on bolls on the bottom portion of the plant, puncturing squares causing young cotton bolls to drop and staining, matting and shrinking cottonseeds through heavy stink bug feeding. Injured locks or bolls may fail to open. Resultantly damage caused by stink bugs introduce bacteria, such as Pantoea agglomerans and fungi that cause boll rots. Currently stink bugs are ranked among the most damaging insect pests of cotton in the southeastern United States.
Researchers from the University of Georgia wanted to determine if cultural practices could be used to manage stink bugs. For instance, by adjusting the planting date, could that mitigate peak pest pressure? University of Georgia researchers compared cotton plots that were planted in May to plots planted in June. The results, published in the Journal of Economic Entomology showed the rate of boll damage generally increased more rapidly through the bloom cycle for planting dates in June compared with May.
"Our study implies that planting cotton early in the planting window will allow growers to escape peak stink bug pressure and thereby possibly eliminate or minimally reduce the number of sprays required to manage them," the study's authors wrote.
In 2011, mean lint yield and economic returns from May planting dates were significantly greater than June planting dates, and in 2012, lint yield and economic returns were greater in plots established in early May compared with later planting dates.
Lint yield was reduced up to 36% in 2011 in late June-planted cotton when compared with lint yield of early May-planted cotton.
The authors hypothesize two explanations for decreased boll damage in early planted cotton. First, the earliest planted cotton began blooming in early July when there are many other suitable stink bug hosts, both agronomic and wild, in the farmscape. Conversely, the June-planted cotton did not start blooming until mid-August when some wild hosts and agronomic hosts like corn would dry to the point of no longer being attractive to stink bugs. Thus, blooming cotton may attract a larger percentage of the stink bug population during August and September.
Second, southern green stink bugs are multivoltine allowing time for an additional generation to develop by the time the June-planted cotton was most attractive. Growers should therefore be aware of increased stink bug damage potential due to late planting.
Read more at University of Georgia.
Southern stink bug image via University of Georgia.