Broad mites damage on bell pepper. Photo: Elsa Sánchez, Penn State
Recently Penn State Extension educator Tom Ford penned this article on broad mites: Broad Mite Infestations Have Growers Considering Biocontrols. As a follow-up, this article looks at how one grower has used biocontrols to manage a severe broad mite infestation of peppers in high tunnels.
At the farm, the grower was able to get one good pepper harvest before nearly all fruit had broad mite damage. As stated in Tom Ford's article, broad mites have a wide host range including beet, bean, cucumber, eggplant, pepper, potato, and tomato. Fruit russeting predominately at the stem end of the fruit was seen on all types of peppers.
Broad mites damage on a long green pepper. Rusetting is predominately at the stem end, but also lower on the fruit. Photo: Elsa Sánchez, Penn State
Broad mites damage on Jalapeño peppers. Photo: Elsa Sánchez, Penn State
Symptoms of broad mites were also seen on plant leaves. New growth on nearly every plant was distorted with curling, elongated leaves, and short internodes. We took a sample of distorted new growth to Penn State's Plant Disease Clinic where the presence of broad mites was confirmed.
Broad mites damage on new growth of a pepper plant. Photo: Elsa Sánchez, Penn State
In order to effectively manage broad mites with pesticides or biocontrols, a preventative approach needs to be used. When plant damage is seen, it is usually too late. Tom Ford gives reasons for this in his article. The grower decided to use biocontrols the following summer.
Neoseiulus (synonym Amblyseius) cucumeris is a predatory mite that preys on broad mites, as well as, other mites, whiteflies, thrips, aphids, and psyllids. They can also eat pollen, plant fluids, and fungi as alternate food sources for short periods of time when prey are not available.
They come in a few delivery systems, this grower used bottles and sachets. Bottles contain predatory mites, bran mites, and bran. Bran serves as a food source for bran mites which the predatory mites eat. This is sprinkled by hand or by the use of a fan on the plants. Once out of the bottle, mites begin searching for prey. With sachets the same bran/bran mite/predatory mite system is used. However, since predatory mites are enclosed they feed on the bran mites for a longer period before leaving sachets through a small opening. As a result they are slowly released over a period of weeks.
Biocontrol suppliers can work with you to develop a plan. A really extensive list of suppliers can be found in the contact information section of Penn State's Vegetable Integrated Pest Management with an Emphasis on Biocontrol guide . The plan that this grower used involved sprinkling predatory mites over transplants after they had been set. Then, once plants grew a little larger, sachets were used.
(Left) Amblyseius cucumeris delivered through sachets were used for management of broad mites. (Right) Sachets were placed near the base of every plant early in the growing season. Photos: Elsa Sánchez, Penn State
The key to any successful biocontrol program is to establish natural enemies before pest populations get too high. Biocontrols were placed on every pepper plant when plants were young, before broad mite populations established. Broad mite damage was absent from the plants and fruit. The grower spent about $400 to implement this program in several high tunnels and was pleased with the results.