46 CIRCULAR 639, U. S. DEPARTMENT OF AGRICULTURE 
practicable with any available type of sprayer owing to the lack of 
working space and the attendant danger of breaking the foliage. 
In a few instances, however, spray applications have been made to 
high tobacco through long lines of hose attached to a power sprayer 
stationed outside the shade field. 
To reduce thrips populations to the lowest possible point, spray 
applications should be begun soon after the plants are set in the 
field. In actual practice there is little incentive to begin spray oper- 
ations unless and until the danger of a drought is impending in May. 
If the spray program is undertaken during the first week in May, a 
period of 2 to 3 weeks is then available for applications before the 
plants are tied up. As many thrips and the egg stage escape sprays, 
FicuRE 51.—Surface irrigation in a field of shade-grown tobacco. This prac- 
tice hastens the maturity of the crop during periods of dry weather and 
thereby indirectly decreases the amount of thrips damage. 
at least six applications have been found necessary to check heavy 
infestations. 
CULTURAL CONTROL 
As the tobacco thrips lives on many weeds and grasses, the elimina- 
tion of these hosts by clean culture on tobacco land and adjacent areas 
prior to and during the tobacco-growing seasons will be of benefit. 
Surface irrigation, as utilized by a considerable number of growers 
(fig. 51), does hot appear to affect the thrips directly, but hastens the 
maturity of the crop during periods of dry weather and thereby 
indirectly decreases the amount of thrips damage. 
THE SOUTHERN GREEN STINKBUG 
The southern green stinkbug (Nezara viridula (L.)) is a serious 
pest of some crops in this region, but it is usually of minor impor- 
