Michigan State University (MSU) Extension Agent Tom Dudek warns greenhouse growers who buy in bougainvillea and mandevilla to remain vigilant about scouting for spider mites, saying he has noticed an increasing number of plants being shipped in with an infestation of spider mites on the undersides of the leaves.
Two-spotted spider mites, with their needle-like, sucking mouthparts, cause graying, yellowing and stippling of leaves and eventual leaf drop in advanced stages of infestation. Ornamentals, field crops, houseplants and weeds all play host to spider mites. And Dudek says there is an increased risk for plants grown in southern states.
In “Scout Your Bougainvillea And Mandevilla Now For Spider Mites,” Michigan State University Extension suggests checking with your supplying greenhouse to see what their miticide applications were for the past month, and if possible, find out what has worked well for them and what has not. This may help you avoid spraying a miticide that the mites are resistant to.
Mites are often found on the undersides of leaves and can be identified by two red spots on their back. If detected, MSU Extension recommends applying one of the following miticides as a foliar spray with good coverage to the undersides of the leaves: Akari, Avid, Floramite, Hexygon, Judo, Kontos, Ovation, ProMite, Pylon, Sanmite, Shuttle-O, Tetrasan or Ultiflora. Check the plants again one week later and spray a second time if mites are still present. If just as many mites are found, then switch to another product from a different chemical group with a different mode of action.
Kontos is a systemic that has shown effectiveness in some cases on this mite issue. However, it takes a few weeks to be taken up into the plant and be fully effective. Foliar sprays will work faster.
For more information, read the full “Scout Your Bougainvillea And Mandevilla Now For Spider Mites story at the Michigan State University Extension website.”