Plant bug damage can be more pronounced when the migration
of adults from wild host plants occurs prior to or about the time cotton is
setting the first pinhead squares (6th to 8th true leaf).
One reason for this is that when adult plant bugs feed on pre square cotton
they feed in the terminal or growing tip. This feeding can disrupt the
physiology of the plant causing abnormal growth (crazy cotton). This abnormal
growth can delay fruiting for several weeks.
On May 20, I surveyed one of the primary spring host plants (daisy fleabane)
for tarnished plant bugs in Alabama. On that date in Henry County (southeast
Alabama) I found that about one-half of the plant bug population was dark
(older) adults about ready to migrate to a new host. In past years, cotton is
about the only host that is attractive at this time of the spring. Most wild
spring hosts are now drying down. The remaining one-half of the population on
May 20 were immatures of all stages. This means that the migration to cotton
could be extended for a several week period which is common in wet springs.
On May 30, I made a second survey in the same area and found
fewer immatures but more light colored younger adults. This may indicate that
the older adults have moved to a new host already and some of the immatures are
now young adults. I made a second survey on daisy fleabane on May 30 about
80-90 miles farther north than the first one. In this survey I found that they
majority of the population was still immature. The fleabane was still greener
and fresher at this location which means the plant bug population was in
perfect sync with the host plants.
Only time will tell what this means in 2013. However,
scouts, consultants and field men should be alert for the presence of adult
plant bugs in cotton, and specifically late planted cotton, in the next 10-30
days.
