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.
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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.