Silverleaf Whitefly Management by: (Phillip Roberts and Alana Jacobson):
The initial goal of a successful
silverleaf whitefly (SLWF) management is to lower the risk of whitefly infestations. All efforts should be
made to minimize the need to treat SLWF with insecticides. Following the guidelines below, especially
when done on a community basis, should result in reduced risk of SLWF locally and areawide.
- Destroy host crops immediately after harvest; this includes vegetable and melon crops in the
spring and cotton (timely defoliation and harvest) and other host crops in the fall. - Scout cotton on a regular basis for SLWF adults and immatures and use recommended thresholds.
- The presence of SLWF should influence insecticide selection and the decision to treat other pests.
- Conserve beneficial insects; do not apply insecticides for ANY pests unless thresholds are
exceeded. - Avoid use of insecticides for other pests which are prone to flare SLWF.
Several additional factors influence SLWF risk: - Leaf pubescence: SLWF prefers hairy cotton. The more leaf pubescence the greater the SLWF risk
(semi-smooth varieties are at higher risk than smooth leaf varieties). - Planting Date: late planted cotton is at greater risk compared with early planted cotton. This is
simply a numbers game as overall SLWF populations increase during the summer months. - Environment: hot and dry conditions are conducive for SLWF population growth. Intense rainfall
associated with thunderstorms can provide suppression of adults. Extended periods of rainfall will
also slow down population growth.
As many of you are aware, we and several agents run whitefly sticky cards around Tifton to monitor
SLWF populations. We update the website below weekly with trap captures:
https://stopwhitefly.org/monitoring/
Invariably there will be fields which require intervention of insecticides for SLWF. The goal is to initiate
control measures just prior to the period of most rapid SLWF population development (i.e. reproduction in
the field). It is critically important that initial insecticide applications are well timed. If you are late with
the initial application control will be very difficult and expensive in the long run. It is nearly impossible to
regain control once the population reaches outbreak levels. - SLWF Threshold: Treat when 50 percent of sampled leaves (sample 5th expanded leaf below the
terminal) are infested with multiple immatures (≥5 per leaf). - Insect Growth Regulators (Knack and Courier): use of IGRs are the backbone of SLWF
management programs in cotton. Effects on SLWF populations are generally slow due to the life
stages targeted by IGRs, however these products have long residual activity and perform very well
when applied on a timely basis. - Use of other insecticide options (non-IGRs) which have quicker effects on SLWF infestations
would be preferred if you are late with the initial spray. These quick knockdown sprays will allow
you to “catch up” and can be followed by an IGR. - SLWF is an areawide cross commodity problem. When everyone uses an effective management
program (regardless of crop) all will benefit.
The table below provides some general information on SLWF recommended insecticide
Cotton Jassid Update
(Phillip Roberts and Alana Jacobson): We are in a better position today
concerning cotton jassid compared to where we were a year ago. To date we have detected jassids in 16
counties in 2026. This time a year ago (August 7, 2025) we had detected jassids in 33 counties. Jassid
populations where we detected them a year ago were also present at much higher populations than now.
Thanks to our agents and others in the industry who have been letting us know when and where jassids
are detected. We maintain a map of jassid detections online at: https://stop2scl.org/cotton/
There is no question that the cold temperatures significantly reduced jassids across Georgia. In February a
hard freeze occurred over most of Florida that likely reduced jassid populations to the southernmost part
of Florida. Initial detections were likely migrating adults which moved in on wind currents. Perhaps 2026
is a best case scenario for jassid as we move forward, but who knows.
We have received a few reports of early hopperburn on field edges and skips in fields. As we move
forward scouting is a must and we should all be looking for hopperburn and leaf puckering symptoms. We
did receive a report today (August 4th) that a field exceeded threshold for jassid in southeast Georgia. In
2025 the first commercial field treated for jassids was on July 31st but at that time our threshold was much
higher than the 1 jassid per leaf threshold we are recommending for 2026
Figure 2 Jassid Hopperburn
Figure 3 below Adult cotton jassid with shed skin to the right,
image by Jeremy Kichler
When scouting for jassids examine the 4th expanded main stem leaf below the terminal. Sample this leaf
on a minimum of 25 plants per field (sampling more leaves is better). If jassids reach a mean of 1 jassid
per leaf treatment is recommended. Once the threshold is triggered it will be important to make a timely
application. As we learned in 2025, jassid numbers and plant injury can progress quickly. If a grower
struggles to be timely with an application, you may need to be more aggressive if populations are building.
The chart below is a general guide of expected efficacy of insecticides we tested in the southeast
during 2025. Some insecticides were tested more than others (i.e. Carbine has 9 data points, Venom only
has 2 data points) so we cannot make direct comparisons. But this chart does have some value. I interpret
this chart that insecticides highlighted in green would be used if jassids triggered threshold. Products in
orange provide suppression but may be of value if a grower cannot come back and make a timely
application based on scouting. It is also important to note that bifenthrin will not provide control of
jassids. Don’t overreact when you detect jassids, scout and use thresholds, and watch trends of how fast
populations are building. All this will allow you to make a good decision. As in 2025 we will provide
updates of the most current information to county agents.
