Adult tarnished plant bugs (TPB’s) are being reported at
moderate to high levels in some fields statewide. More findings are reported
each day and there are likely many fields where they are present but have not
been observed yet. At this point, no one has reported high pinhead square loss.
This square loss is what we like to base our treatment decisions on. However,
based on past experiences, once the adult TPB’s are present it is just a matter
of time until some level of square loss is detected. These are all migratory
adults that have moved into cotton from wild hosts. They will feed on pinhead squares,
which cause abortion, and also deposit eggs in the plant stems. These eggs will
hatch in two plus weeks into an immature field generation. The longer the
period that adults are allowed to roam in fields, the longer the period of
hatching immatures will be in coming weeks. Knowing this, growers can make
their own decision as to when controls should be applied.
The second insect I will mention is the tobacco budworm (TBW).
An extended flight of budworms has been ongoing in various areas for about two
weeks already. This is of no significance to 98% of the states acreage that is
planted to Bollgard II or WideStrike varieties. However, this makes a tricky
situation in conventional cotton that may need plant bug sprays during this TBW
period. This TBW flight is also impacting later planted peanuts that have a
limited amount of vegetative growth. Budworm moths seem to be attracted to
peanuts with a vegetative width of 3-4 inches. Earlier peanuts that have six of
more inch vegetative width do not appear to have as many budworms present. We
collected about 250 quarter inch budworms yesterday at Headland, Alabama on
about 600 row feet. This was not what I would consider an economic or treatable
level. However, up to four budworms per row foot have been reported in some
fields and controls, with the newer chemistry, have been applied.
The third insect that is causing widespread concern in
cotton at present is the three-cornered alfalfa hopper (3CAH). Numerous fields
in the Tennessee Valley area of northern Alabama have had damaging levels of
3CAH reported. This problem has extended as far south as Talladega County.
Treatments have been applied. Soybeans are also experiencing a problem with
this insect, even more so than cotton, and over a much larger geographical
area. 3CAH damage is caused by the girdling of the main stem of both cotton and
soybeans by both the adult and immature 3CAH. No good thresholds exist from Alabama
research. Usually this problem and damage is greater on field borders but
consultants have reported damage field wide in both cotton and soybeans.
Treatment thresholds are difficult to develop for 3CAH, just as they are for
grasshoppers. Treatments sometimes have to be made based on the risk that
certain species present, and not the level of damage observed. Sweep nets are
very effective in documenting the number of 3CAH per row foot.
