Thrips injury causes leaf edges to brown and makes leaves curl and pucker. On heavily infested plants the undersides of leaves, especially the first cotyledonary leaves, have a silvery appearance. Best control results have been obtained by using a systemic in-furrow insecticide at planting. For rescue treatments, spray just as the cotton comes up to a stand and make a second application one week later. Cotton fleahoppers and plant bugs Cotton fleahoppers and tarnished plant bugs sometimes injure plants by sucking juices from the very small squares, causing them to blast.
Most severe injury occurs in the first four weeks of the fruiting season.
This square blasting causes plants to remain in a vegetative state, delaying fruiting and fiber maturity. Carbohydrate stress can also cause squares to be shed under cloudy conditions. Be sure that insects are causing trouble before you use insecticides. If you spray for plant bugs, check sprayed fields weekly for aphids and bollworms throughout the remainder of that season. Damaged leaves curl down at the edges.