Silverleaf Whitefly in Cotton Update Roberts
Silverleaf whitefly (SLWF) adults have been observed in low numbers in cotton in some areas during the past week to ten days. To date very few immature whiteflies have been observed in cotton. We are not aware of any field which has exceeded threshold for SLWF. Most reports include observations of individuals or a few adults when searching plants for corn earworm. However, the presence of SLWF in a field is worth noting and management of all insect pests must consider the presence of SLWF. All efforts should be made to minimize the need to treat SLWF with insecticide.
Management Considerations:
1. Scout for the presence of SLWF adults. It is important to know if SLWF is present!
2. Conserve beneficial insects, do not apply insecticides for any pests unless thresholds are exceeded (beneficial insects will also suppress corn earworm).
3. If SLWF is present in a field, avoid use of insecticides for other pests which are prone to flare SLWF.
4. Scout fields frequently for immatures once fields are infested with SLWF.
5. Be timely with SLWF insecticides when thresholds are exceeded (many learned in 2017 that it is difficult to play catchup with SLWF).
6. Be very aware of SLWF infestations in hairy leaf varieties and late planted cotton, these are high risk fields.
There is no question that agents, scouts, consultants, and growers are looking more closely for SLWF this year based on the problems we had in 2017.
Historically if we see SLWF in cotton during the month of July we should anticipate problems with SLWF, especially on late planted fields, and manage appropriately. Infestations do not come close to where we were a year ago. In 2017 treatable populations first occurred during the last week of June and many acres were treated in July; so, we are in a much better situation this year compared to last. It will be important that all fields are monitored closely for SLWF and hopefully proper proactive management can minimize damage and the need for SLWF insecticides. Your County Agent has additional information on management and scouting of SLWF in cotton.