However, other kinds of insect pests are also attracted to yellow cards, therefore it may be more practical to use yellow cards for general pest monitoring. The number of thrips per card should be recorded and graphed weekly to monitor population levels and movement in or out of the greenhouse, and thus aid in control decisions. Flowers can also be checked for thrips by tapping a blossom over a sheet of paper, although it is more efficient to use sticky cards to detect and monitor numbers of thrips. Yellow or white flowers seem to be particularly attractive to the thrips. Although effective thrips management can be difficult, adequate control can be achieved by a combination of physical, cultural and chemical control measures.
Prevention is the obvious first step in a management program.
It may be easier to prevent an infestation than to manage an established one. The thrips will overwinter in the greenhouse and may result in a large infestation the following spring. Growers should also avoid purchasing plant material infested with thrips. Research in California has shown that the use of 400 mesh fine screen or barriers over vents can help prevent the movement of thrips into a greenhouse. Research in North Carolina is examining the use of materials such as Visqueen to cover plants on greenhouse benches.