2015 Corn Disease Risk
Our
above average rainfall this season has obliged most of our grain crops. Although many of our Hale &
Swisher fields are later than we would prefer, irrigation systems have remained
quiet for the most part. This has saved
untold millions of gallons of irrigation water while maintaining a solid yield potential. These wetter than ‘normal’ conditions also
come with a down side, particularly in corn.
Corn ‘diseases’ in our area are running high. This stands to reason as most of these
diseases are fungal related and require moisture and humidity to spread and
certainly for the spores to germinate. Continually
keep driblets of water present on the leaves and the diseases thrive.
On
that ‘usual’ year, the only disease we can count on seeing in our area corn year
in and year out is Common Rust. This
pathogen is not usually economic for us but can become economic in the right
conditions. With the additional rains,
morning dews, and higher humidity, the conditions have certainly been right for
Rust this season. For most of our Plains
Pest Management scouting program corn acres, I am estimating a 2 – 3 fold
increase in common rust as of this week.
That is not the only pathogen we are finding in field, and certainly not
all we are getting reports of.
We
are also identifying Southern Rust, Northern Corn Leaf Blight, Grey Leaf Spot,
and a handful of other ‘blights’ to lessening degrees. Several of these lesser blights have flared
on a few spots or in some cases for just a few days and ceased when conditions
dropped back below ‘ridiculously wet’ with little impact made other than the knee
nocking turmoil of potential trouble brewing in the field. The Southern Rust and Northern Corn Leaf
Blight look to have more staying power this season with the conditions we have,
and potential to become economic if they have not already. In our older or more developed program corn
fields the impact of all of these diseases has been minimal so far, but these
fields have all been treated with fungicides in a preventative manor recently
before any real harsh problems developed.
This is not the case for all area fields.
Last
week we were getting reports from across Hale, Floyd, and farther south that
Northern Corn Leaf Blight (NCLB) looked to be hitting post tassel corn pretty
hard with long term affects to be felt in yield and harvestabality later. Emergency treatment applications were soon
abound for those scouting closely enough to catch and identify the problem in
time. The NCLB now seems to have slowed this
week with ‘the line in the sand drawn’ through good scouting and slightly dryer
conditions predominating the area.
Still
a growing concern today is Southern Rust.
Clay Golden, independent crop consultant based in Floyd County, spoke
with me recently about what he is seeing in Floyd County, “We have quite a few
fields that we treated with fungicide two weeks ago and quite a bit for NCLB
last week. There are a few fields treated
two weeks ago that are now in the dough stage. We have Southern Rust rebuilding now (that
residual from our treatment is running out).
We really don’t want to, but we might be forced into making a second
application in a few spots if the trend continues.”
I
also spoke with Dr. Jason Woodward, extension plant pathologist district 2,
this week about the increase in corn disease pressure this season. Dr. Woodward explained, “The wetter weather
has increased the corn disease pressure throughout the region and there has
been a lot of fungicide go out to combat them.
Much of the older corn in the Lubbock area has reached dent stage and I feel
pretty confident stating that those fields should
be on the downhill side of the rust and blight risks. Even if those post dent fields have an increase
in disease it might not be an economic situation as that field starts to dry
down, especially if they have already been treated. On the other hand, the whole region has quite
a bit of late corn that hasn’t even tasseled yet. Those fields are going to be a major concern
for disease issues as we move forward if the moist weather persists. As the days start growing shorter, the nights
cooler, and morning dew becomes common, in conjunction with a continued wet
weather pattern, and we could see some major issues with several of these corn
diseases over the next few weeks and months on those younger corn fields as
they progress through key and later reproductive growth stages… Now that many
of these diseases are present in the region at a noticeable level, I might even
expect to see even higher disease problems in pivots compared to say drip
fields where we will be making applications of water to the plant even if the
much appreciated rain patterns slow.”
This
situation described by Dr. Woodward certainly holds true for the late corn fields
in our scouting program corn acres and looks valid throughout Hale, Swisher,
& Floyd with greater than normal late corn acres due to be hitting those
key reproductive stages soon. We really
do not want to chase away any future rainfall that we know we will need but we
should be aware of the potential problems that could arise with the blessings
of a good rainfall pattern.
Please call or come by if you have
any questions,
Blayne