Evaluating the extent of freeze damage to our area wheat is still the main issue for wheat producers. Just about the time producers, crop consultants, and advisors are ready to make a solid freeze assessment another round of freezing weather moves in. As of April 23, it is difficult for me to find irrigated wheat fields in the area with no freeze damage whatsoever to the growing point or stalk. The severity of damage sustained looks highly variable from area to area, field to field, and also across individual fields. Areas irrigated shortly before any one of the recent cold snaps seem to be in the worst shape. Many times ice from the recent pivot irrigations formed on and over the plants in a sheet causing serious damage to that area of the field. Fields already experiencing serious drought stress had less crop canopy to ‘blanket’ the heads and growing points and have significant freeze damage also. Damage generally seemed more prevalent the farther north I moved across Hale and Swisher counties. Exceptions to this observance can be found, both better and worse, just about anywhere across both counties. Experience does show that we should never count wheat completely out until the heads actually emerge. Many fields are moving into flag and boot stages now.
Of the fields I have looked at this week, the percent damaged heads ranges from 5% to 60%, with most irrigated fields averaging about 15% in Hale and 25% in Swisher. This is not a 1:1 head damage to yield loss relationship. Historically, that relationship is more 2:1 in nature. Secondary tillers, if healthy, can help compensate in yield and grain weight. It remains debatable what the yield potential of the area wheat crop was before the recent frost events occurred with so many detrimental factors working against the crop.
If present, freeze damage to the stalk will be much more severe in economic terms than damage to the head or growing point. Fields with this type of damage are very likely to lodge as the grain matures and become un-harvestable for hay or grain. In addition, that stalk becomes limited in the amount of grain fill it is capable of. Symptoms of freeze damage to wheat stalks include a brownish-red discoloration and are easily collapsed compared to healthy green stalks. I have noted a few low lying fields already lodged well before boot and have had several producers report the same. In these cases, the wheat is lost to any use other than grazing or cover.
Greenbugs and other aphids can still be found in most area wheat fields, but appear to have run their economic course. Area insecticide treatments seem to have worked well where applied. Many producers opted not to treat for economic infestations of greenbugs this season due to the already bleak wheat situation and economic outlook. In fields where greenbugs were allowed to run their course significant pest damage has occurred, but predators and parasitoids are now working their way through the aphid populations and look to have the pest on the downward slope. I urge producers and consultants to remain vigilant in their pest and plant monitoring efforts. Each field is likely to have unique populations and situations and the threat of economic damage from greenbugs are still present.
On April 12, Monti Vandiver, CEA – IPM in Bailey and Parmer counties, released his findings confirming a few pocketed populations of chlorpyrifos resistant greenbugs surviving 1 pt/ac. applications in those two counties. One ray of sunshine on an otherwise bleak assessment of the current wheat situation is that several area producers opted not to treat their greenbug problems. This offers a chance for our likely susceptible or at least less exposed populations of greenbugs to survive and possibly help stem the encroachment of resistance into our area and perhaps ease the pressure on those producers nearby.
I welcome any thoughts or questions you may have regarding your wheat situation and I encourage consultants to share your field observations with us too. Thanks,