By Shawn P. Conley and Damon Smith
The 2014 and 2015 WI winter wheat crops both endured significant Fusarium head blight (FHB or scab) incidence as well as mycotoxin (vomitoxin) dockage and outright rejections. Here are a few considerations for managing FHB before the 2015/16 crop even goes into the ground.
1.
Crop rotation matters. Data from our long-term
rotation studies indicate that wheat
following soybean provides the greatest yields. The next best options
are wheat following corn silage (6.5% less) then corn for grain (21% less).
Wheat following alfalfa or another leguminous crop are also good options, though
the N credits following alfalfa may best be served going to corn. Furthermore,
background fungal pressure (residue on and in soil) from the FHB fungus will be
greater following corn then soybean or another legume, however know that spores
that infect your wheat crop can arrive from outside the field. Please click to see more
information on the Top 8 Recommendations for Winter Wheat Establishment in2015.
2. Variety
selection matters. Data from our 2015
WI Winter Wheat Performance Test shows variable
yield and disease performance among the varieties listed. Select those
varieties that have both good to excellent FHB resistance and high yield. When
evaluating FHB resistance, low numbers for both FHB incidence and severity can
be helpful, but the major focus should be placed on FHB incidence (measure of
the number of FHB-symptomatic plants in a stand).
3. Application timing matters. One of the biggest challenges
year in and year out is improper fungicide application timing. Our data
suggests that on susceptible (Hopewell) or moderately susceptible varieties
(Kaskaskia) equal efficacy of the fungicide Prosaro at a rate of 6.5 fl oz/acre
can be achieved when applied between Feekes 10.5.1 (anthesis) and 5 days after
anthesis. Given the variability of head emergence and anthesis across a
landscape it may prove best to wait a few days until the whole field is
flowering than to apply too soon. If the
extruded anthers have turned from yellow to white across the whole field then
you are likely too late. Remember it roughly takes a wheat head 7 days to
completely self-pollinate.
Fusarium head
blight incidence ratings for four soft red winter wheat varieties treated
with Prosaro SC fungicide at 6.5 fl oz/a at anthesis (Feekes 10.5.1), five
days after anthesis, or not treated in Wisconsin in 2015.
|
||||
Hopewell (Susceptible)
|
Kaskaskia (Moderately
Susceptible)
|
Pro 200
(Moderately Resistant)
|
Sunburst (Moderately
Resistant)
|
|
Prosaro SC @ 6.5 fl oz/a
(Feekes 10.5.1)
|
9.5b
|
2b
|
0.5
|
4
|
Prosaro SC @ 6.5 fl oz/a
(5 days after Feekes 10.5.1)
|
7.5b
|
5.25b
|
2.75
|
2.75
|
Non-treated control
|
31.25a
|
17.5a
|
3
|
1.5
|
Pr>F
|
0.01
|
0.01
|
ns
|
ns
|
LSD
|
6.44
|
6.44
|
ns
|
ns
|
4. Choose the right fungicide class. Make sure you use the
appropriate fungicide product and class to manage FHB. The label for products
containing strobilurin active ingredients (FRAC group 11) ends prior to
flowering. Late application can actually lead to increased mycotoxin levels.
Triazole containing products (FRAC group 3) are recommended for FHB control.
For a list of products and efficacy ratings, visit the Field
Crops Fungicide Information Page.
5.
Harvest timing and
flash drying. The word on the street is that in 2016 elevators will push
growers to harvest early (18% moisture or higher) and subsequently dry grain to
mitigate mycotoxin levels. While drying grain to 13% or less moisture is a good
storage practice, know this process may kill the pathogen but any mycotoxin
levels already in the grain will not dissipate. Vomitoxin is a very stable
molecule and IS NOT degraded by heat, freezing, or drying.
