It’s go time. It appears that there is some correlation between meet the teacher and cotton jassid outbreaks in Alabama. Last year, I received my first call on jassids in “the real world” on August 12, while I was in meet the teacher for my kids school. This year, the first call with reports of cotton jassids at economic levels came on August 11 (the day my kids also had meet the teacher).
Current reports are that spotty, but economic, populations
of cotton jassid have been observed in Coffee and Dale counties. As a reminder,
threshold (or economic levels) is an average of 1 cotton jassid per leaf. We
currently recommend focusing on the 4th node mainstem leaf below the
terminal. However, if jassids are found on other leaves, do not ignore them. We
are currently in a weather pattern that is favorable for cotton jassid
development (hot, dry and somehow still humid) and populations can explode in a
short amount of time. Our threshold counts adult and immature jassids the same,
but the presence of adults is important to confirm the species of leafhopper in
the field is cotton jassid. When the wing-pads are present, you can see two
small black dots developing. This is one way to positively id cotton jassids
nymphs.
Immature cotton jassid with black dots developing near wing pads
In addition to looking for cotton jassids, we also need to
be scouting for early signs of hopperburn. Symptoms begin as a general
yellowing of the leaf, followed by distinct yellowing, then reddening of the
leaf margins. Following the signs on leaf margins, hopper burn moves throughout
the leaf before leaves fall off the plant. Catching hopperburn early is
critical, as when red is easily observed on leaf margins, damage cannot be
stopped on those leaves.
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| Varying levels of hopperburn caused by cotton jassid. |
In our observations and from reports, cotton jassids seem to
be concentrated on the earliest planted cotton right now. This trend is similar
to what we observed early last year. Reports are that cotton jassids tend to be
on cotton with small bolls at the top. Hopefully, this means one well-timed
application can knock them out and these fields will not require multiple applications.
Treatment options will likely depend on other pests in the
field (stink bugs, plant bugs or spider mites) and the level of jassids
present. For these fields that are close to the end, Bidrin is a good option to
control jassids and the bug complex. If spider mites are a major concern,
Vertento is an option to knockout all the pests. If high levels of jassids are
present (multiple per leaf) and other pests are not as much of a concern, then
we have several options that provide good control (Argyle, Carbine, Courier,
Sefina, Sivanto and Venom) and others that provide moderate control (acephate,
assail, Centric, imidacloprid and Transform). One key thing to keep in mind is
that pyrethroids (bifenthrin and others) do not control cotton jassids and can
make populations worse. I would not spray pyrethroids for stink bug control from
this point forward in southeast Alabama.
To see an up-to-date map on cotton jassid detections across
the Cotton Belt, you can check out the Stop two-Spot Cotton Leafhopper
(Stop2SCL) website here (https://stop2scl.org/cotton/)
As always, if we can ever be of any help, or if you would like to provide input on the situation in your area, please don’t hesitate to reach out to your local Extension Agent or myself (Scott Graham: 662-809-3368) and Ron Smith (334-332-9501). For more information on thresholds and insecticide recommendations, visit the Alabama Cotton IPM Guide (IPM-0415). To stay up-to-date on the Alabama cotton insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter and Podcast, and the Syngenta Pest Patrol Hotline.
