Early summer sericea control

A lot of work has been done to fight the spread of sericea lespedeza since it became a Kansas noxious weed in 2000. Unfortunately, many of the plant’s attributes have allowed it to survive many of our most well-intentioned control efforts.

It won’t be long until the control window is wide open and another control opportunity will be at hand. With multiple control options (mowing, prescribed fire, grazing with different livestock species, etc.) available, an integrated control approach is often the best one, and often includes a herbicide component.

Early season (while sericea is in the vegetative stage) control often includes triclopyr only containing products (Remedy Ultra) or products containing triclopyr plus fluroxypyr (PastureGard HL). Products containing picloram plus fluroxypr (Surmount) is also an option. Spray volumes of 10 to 20 gallons per acre will provide the best results — aerial applications should be at a minimum spray volume of three gallons/acre. Repeat treatments will likely be necessary.

If sericea control is on your to-do list, start planning now. Great information can be found via your County Noxious Weed Department. There’s also an entire page in the 2023 KSU Chemical Weed Control Guide dedicated to chemical control of sericea. Contact us for a copy or check it out online at https://www.bookstore.ksre.ksu.edu/pubs/CHEMWEEDGUIDE.pdf.

Bagworms Already?

We generally notice bagworms when they are three quarters to an inch long in late summer, but if they’ve given your evergreens fits in the past, scout now. Bagworms are much more easily controlled when very small (less than one quarter inch), and they’ll likely be hatching and growing quickly to that point sooner than we’re ready.

Feeding typically starts at the tops of trees and shrubs, meaning damage is likely already occurring up in the canopy by the time we see it at ground level. They don’t all hatch at the same time and they can move from tree to tree via silken threads that allow them to “balloon” from plant to plant. If left unchecked, they can cause a lot of damage in a little time, particularly to evergreens that won’t produce another flush of growth after they are defoliated.

If you’re looking for insecticides, look first for a product labeled for bagworms and also with a label for the plant(s) to which you are applying. Some products (Bacillus thuringiensis subsp, kurstaki and Spinosad) can work very well, but have to be used on small larvae. Numerous other products are available as well, and may have some efficacy on slightly larger larvae, but none will likely get larger larvae often well protected by their bag.

No matter what you use, good coverage is key. Products have to either contact the larvae or be ingested, so make sure application covers trees from top to bottom and interior to exterior. Reapplication may be necessary if the hatch occurs over a long period or residual activity of insecticide wanes.

For additional information, request a copy of our KSU bagworm publication or check it out online at http://www.bookstore.ksre.ksu.edu/pubs/MF3474.pdf.

David Hallauer54 Posts

David Hallauer is the Meadowlark Extension District agent in the areas of horticulture and crops and soils.

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