It has been three weeks since we had our last rain in SW Nebraska and we are seeing all dryland crops showing signs of drought. Reference evapotranspiration (ET) in the Upper Republican NRD ranged from 1.6 inches in Perkins Co to 2.9 inches in SW Dundy Co. This means that crops in SW Dundy Co used about 1.5 inches of water more than in Perkins Co. See image for more details on ET and rain data as well as crop growth stages and their water use coefficients for this period.
According to US Drought monitor none of the Counties in SW Nebraska are in abnormal drought, which can means that these conditions are (believe it or not) normal in SW Nebraska this time of the year. According to 30-year weather data, average August precipitation and ET are 2.50 and 9 inches, respectively. This means that the area had the August weather conditions in very close proximity to long term average.
We had very good growing conditions in May, June, July and August, so crops used all that water and heat to produce large biomass and increase yield potential. Rain is much needed to keep up with high water demands during the grain filling period in September, otherwise we will have to be satisfied with the mediocre dryland yields at the end of the year.
Reference evapotranspiration (ET) in the Upper Republican NRD ranged from 4.18 to 5.24 inches in this 17 days period (from 0.25 to 0.31 inches/day), with area to the south and with less rain having larger ET. Two storm came through SW Nebraska on August 5th and August 8th, each carrying from 0.5 to 3.0 inches. Rain really helped all dryland crops as it came at the right time and after good growing conditions we had in June and July. Hopefully the trend will continue to produce outstanding dryland yields for this area.
To more accurately estimate rain and crop water use on your farm, look at the map (attached) provided, obtain weekly reference ET value from location closest to you and multiply that value by crop coefficient provided in the table.
To estimate crop water use or crop ETc look at the map provided, obtain weekly ET value from location closest to your farm and multiply that value by crop coefficient provided in the table. Assuming your soil has enough moisture on the supply side this is how much water your crop used in a past week (June 29 to July 6). Reference ET values have been around 2.15 inches.
It is getting warmer and dryer in SW Nebraska. Last week we received 0 to 0.8 inches of precipitation, while reference evapotranspiration (ET) losses dropped 2 inches. Many farmers are irrigating corn and other crops to build up the soil moisture profile so they can keep up with water demand during the peak of the growing season. Awoid chemigating roads and neighbor fields. Wheat Most of the wheat is at dough stage, but harvest will start next week in some areas! Hard winter kill in some areas, dry early spring and very wet April and May created favorable conditions for diseases that we don’t usually expect in this semi-arid climate to develop to flourish. Many farmers were not ready for it and diseases like black chaff, stripe rust, Fusarium head blight (scab) and Septoria leaf blotch are going to cause severe yield reductions. We learned that knowing varieties you planted is the best way to fight diseases; if variety is susceptible to stripe rust, be ready to spray.
Corn Corn is at V3 to V10 growth stages. Fields reveal the consequences of planting in wet conditions. Restricted root growth due to compacted seed bet is very common. Rootworm injury has been observed in continues corn. Look at which Bt-protein is expressed in your Bt-corn hybrid. If eCry3.1ab, mCry3A or Cry13Ab1 proteins are not expressed in your hybrid chemigate with Capture LFR or Brigade to control larvae of the rootworm. Even though, tillage and cultivation are a big “NO” in this part of the country, popcorn producers started cultivating due to lack of options to control kochia and Plamer amaranth.
Soybean Soybeans are at V1-V6 growth stage. Time to inspect soybeans for nodulation. Cut nodule in half and if color of tissue is pink, nodules are active and nitrogen fixation is present. Kochia is very hard to control and it’s gaining biomass rapidly with warm weather. Severe herbicide injury has be observed on soybeans in this area. Avoid applying generic herbicides that you haven’t used before at high temperatures to reduce the risk of hearting a crop. Other crops Milo from emergence to V6. Field peas are filling pods. Potatoes are in tuberization stage. Dry beans are at VE-V3 and in good condition. Sugarbeets are at 75% cover, and some insect damage and Cercospora leaf spot is visible on leaves, but no management action is needed at this point.