Scout For Fungus In Small Grain And Ryegrass

Dec 22, 2015

By Dennis Hancock

We have had numerous calls this fall regarding fungus issues in small grain, particularly Oats and ryegrass that were planted early for grazing. Based on the warm moist weather we have experienced through much of November and December, I would be very diligent in scouting for symptoms on later plantings for grazing and grain. As the article below indicates we are very limited on “legal” fungicide options for grazing, but do have some options if the small grain crop is being grown for grain or silage.

Disease issues are cropping up all over in S. GA, particularly in oats and ryegrass. I have had reports of crown rust on oats in far SW Georgia and barley yellow dwarf on oats and various leaf spots across S. GA on ryegrass and some cereal grains. For oats and battling crown rust (usually only an issue in Georgia if within 75 miles of the Gulf or Atlantic Coast), they may need be prepared to apply LEGAL fungicides, if needed. Please avoid prophylactic spraying until a disease is indicated and properly identified.

Barley Yellow Dwarf Virus is also prevalent this year due to a warm fall and symptoms may appear similar to rust with poor growth and leaf damage. Fungicides will not cure or treat this aphid-vectored, viral infection. Aphid activity can be stymied by lambda cyhalothrin (e.g., Karate, Warrior, etc.) and it appears the other pyrethroids are not as effective.

Producers who are growing oats for grazing who have confirmed disease infection might closely graze the oats to reduce the inoculant load and utilize the forage. Any damaged forage will deteriorate substantially after a hard freeze. If it is feasible, they might consider overseeding with ryegrass to compensate for the production loss in forage. Still, if they overseed, the grazing animals will need to be removed to allow the ryegrass to establish. Possibly, grazing oats could be treated with a fungicide after close grazing. Withdrawal restrictions must be followed as directed on the label. This may only temporarily arrest the rust, as inoculant appears wide-spread. Retreatment may add significant costs to winter forage production and economically, feeding conserved forages and supplements may be more

cost effective. For silage or seed oat, there are a number of LEGAL fungicides that may be effective. These include Headline, Proline, Stratego, Quadris, Tilt and Quilt. However……producers must follow labeled instructions for harvest withdrawal periods. Also, these fungicides are in the $20+/A treatment cost for a single application plus the cost of applying the product. Stratego and a few others might be a little less expensive. Multiple applications may be necessary for oats grown to silage or seed stage.

It is likely that we also have winter grain mites at present, too (though no reports of that yet… emphasis on yet). Farms where manure has been applied at high rates are predisposed to having an issue with this. Potentially, the extra biomass residual from overgrown pastures/hayfields this summer could also provide OM habitats for this insect, as well. We’ve also had weather conditions that definitely favor its growth.