The cotton jassid is native to the Indian Subcontinent where
it is a major pest of cotton, okra and eggplant. According to the Florida
Department of Agriculture, it was first detected in US Virgin Islands and
Puerto Rico in 2023 and in cotton in Jackson County (FL) in the late fall of
2024. Cotton jassids are small (1-2 mm) leafhoppers that look similar to other
leafhoppers, like potato leafhopper. Adults can be distinguished by a pair of
two black dots on the wings, with the wings being visible to the naked eye.
Unfortunately, differentiating immature cotton jassids from other species of
leafhoppers is difficult until they reach later instar stages when the two
black spots can be seen near the wing pads. Thus, proper identification of
adults is important to have an idea of what species immatures are present. Cotton
jassids injure plants by feeding on the underside of leaves, breaking down leaf
tissue with salivary toxins. Symptoms begin as a bronzing or yellowing of the
leaf, followed by curling and then yellowing and reddening of the leaf margins
(hopper burn), ultimately resulting in leaves turning brown and falling off the
plant.
There is still much to learn about how the lifecycle will be
impacted in the US. Cotton jassids are reported to lay eggs into leaf tissue,
with a single female laying between 13 and 34 eggs in her life. Eggs hatch in
3-4 days and nymphs develop through 5 instars in 8-10 days. Adult cotton
jassids are reported to live between 2 and 4 weeks with new generations
approximately every 2 weeks. There is a long list of “host” plants in the
literature, including southern row crops cotton, corn, soybean and peanut. Other
plants like okra, eggplant, cowpea and Bermuda grass are also listed. However,
we do not currently know which plants are “true” hosts and which are “incidental”
hosts. This is critical, as true hosts would be the only hosts cotton jassid
could turn over a generation on, and likely the only ones that could be
economically damaged. To this point, observations have been that corn, soybeans
and peanuts are more likely to be incidental hosts. No reproduction or injury
has been documented in these crops in the US.
While there is much to learn for 2026, collaborative
research and observations from research and Extension Entomologists at Auburn
University, Clemson University, the University of Florida and the University of
Georgia has provided some answers going into the new year. When an invasive
insect appears, there are three major questions that must be immediately
addressed: 1. How do we kill this insect? 2. Does it even matter (does it limit
yield)? 3. When do we kill this insect (thresholds)? Thanks to a combination of
on-farm and experiment station trials, a solid list of insecticide
recommendations has been developed across the southeast. Similarly,
observations in trials and in commercial fields have led to the development of
a preliminary treatment threshold (1 nymph per leaf). Research trials planned
on experiment stations were quickly reshaped to study yield impacts on cotton
jassid when they appeared. Cotton was even planted in early to mid-September on
experiment stations to collect information on at-plant and foliar insecticides
for seedling cotton infested with cotton jassid.
There are still more questions than answers for the 2026
season. Will it survive the winter? If so, how far north will it survive? What
will its winter hosts be and how will cover crops be associated? How persistent
will it be early in the season? How many insecticide applications will be
needed to avoid economic loss? Other than insecticides, what can be done to
reduce the risk of infestations? These questions and more will be addressed in
a collaborative effort across the Southeastern US in 2026.
For now, we have observations that will be guiding Extension
recommendations going into 2026. Proper fertility management will be important.
Many insects, likely cotton jassids included, are attracted to rank, lush
plants. Cotton fields with excess nitrogen will likely be more attractive and
have higher populations of cotton jassids. From our observations and
understanding from the literature, the opposite is true for potassium. Cotton
plants that are deficient in potassium seem to be less able to overcome cotton
jassid injury. Thus, soil sampling and proper fertilization are expected to
play an important role in cotton jassid management next year.
We do not know what cotton jassid populations will be like
in 2026, it is likely that they will be slow to build and hopefully not a
problem on seedling cotton. Observations from research trials this fall in
Alabama, Georgia and Florida suggest that seed treatments provide moderate
suppression of jassids. With the expectation that populations will probably be
slower to develop, cotton should be planted early to attempt to avoid cotton
jassids on young cotton. Cotton should be planting should be again around April
15 as soon as conditions allow. In addition to early planting, growers should
consider using short season varieties. An early planting date and fast maturing
variety will reduce the length of time cotton is susceptible to cotton jassid
and likely reduce the number of insecticide applications needed for control.
Speaking of insecticide applications, several options have
been identified with replicated on-farm and small plot trials across the
Southeast. Cotton jassid is resistant to nearly every class of insecticide used
for control in its native range. This means insecticide rotation will be
critical to preserve economical options. As more observations were made in
2025, the threshold continued to drop. The first recommendation was 5 nymphs
per leaf. This quickly dropped to 3 per leaf, 2 per leaf, 1-2 per leaf and finally
1 per leaf. Further testing is planned in 2026 to validate or further reduce
this threshold to minimize economic losses to cotton jassid. Cotton jassids
tend to build on field borders and are often found first on isolated plants on
the edge of the field. These “indicator” plants can be used to help scouts know
when to intensify monitoring efforts in the field. Based on observations in
2025, cotton jassids tend to be found on the mainstem leaf on nodes 3, 4 and 5
below the terminal. To scout fields, target the mainstem leaf on the 4th
node from the terminal. Carefully flip leaves over and note the presence of
adult and immature cotton jassids. Because populations can build so quickly,
and fields crash so quickly, grower logistics should also be built into
threshold considerations. For example, if sprayers can only get across fields
every 10-14 days, applications may need to be made if cotton jassids are found
at threshold on 30-50% of the plants scouted.
As stated, many times, we simply do not know what 2026 will
look like. One thing we know for sure: growers should not plant cotton if they
do not have trained scouts monitoring fields at least weekly. Cotton jassids
build too quickly and pose too much of an economic threat to try to manage by
calendar-based sprays or trying to scout by yourself. Timeliness will be of the
essence. When a scouting report indicates intervention is necessary, action
should be taken as quickly as possible.