Solutions for Dealing with White Flies in School Greenhouse

Q: Our school greenhouse has an infestation of white flies that are destroying all of our green peppers and cucumbers. The school even had an exterminator a few months ago who came and sprayed. It decreased the number for a while but they are now back in full force. How to rid school greenhouse of white flies?
A.B., Nixa, Mo.

A: White fly control is a challenge in greenhouses, and requires an integrated approach.  The publications at http://extension.missouri.edu/p/G7275 and https://entomology.ca.uky.edu/ef456 are good.  Basically, here is the approach:

1.            try to keep the pest from entering the greenhouse - closely examine all plants that are brought into the greenhouse, discard heavily infested plants.

2.            monitor the greenhouse with sticky yellow cards, on a daily basis if possible.  When a threshold of around 0.5-2 insects per card per day are noted, a spray is applied. Cards are available from http://m.gemplers.com/search/sticky+yellow+cards and elsewhere.

3.            The attached publications lists effective sprays for this pest.  Sprays must be alternated as this pest is at high risk of developing insecticide resistance.

Patrick Byers

Regional Horticulture Specialist

MU Extension - Greene County

417-881-8909

byerspl@missouri.edu