field continues to mature. Kernels are filling (getting bigger). It
appears the lower leaves are starting to show
drought symptoms. We caught a little shower today, but only 0.14
inches. That will hardly settle the dust.
The back of this head is more of a buttery-yellow than it was last week.
The bracts are still green, but they are
starting to turn yellow too. This
plant is in the R8 stage of maturity. You can see several brown
lesions caused by head moth larvae.
In this cross section of the head you can see the kernels are developing
well, but there are signs of head moth
larvae. Lets look inside
a kernel before we start looking for larvae.
By opening the hulls you can see the well-shaped, white seed. This seed
is developing well, but as it matures it will turn more gray.
Well, what do we have here? This head moth larva appears to be a little
This is a little better picture of a head moth larva. They have
alternating long brown and light stripes. Also, they
have a brown head
capsule. They burrow through the head and damage tissue and
This is a head near the field edge that has been
infected by Rhizopus
head rot. If you didn't see the
neighboring heads that are in the R8
stage, you might think this was a mature head. This disease can be
quite severe resulting in high yield losses. There's not much a farmer
can do about it other than try to control the sunflower head
This is a closer view of the same head. There's no mistaking that
this is a diseased head. There will be no
harvestable seeds in this
head, rather the seeds will be small and shriveled.