The 2005 season for Louisiana feedgrains could be described in one word as peculiar. We started too wet, which delayed corn planting, and then went through a major drought so severe we were a week away from losing some crops. Fortunately, the situation had improved dramatically as of July 19. Intermittent rain had fallen over most severely drought-stressed areas, but some areas still need rain. The best news is that input costs have been minimal thus far.
Unfortunately, most of the corn crop did not receive adequate rainfall during peak water use growth stages (kernel filling, primarily) and yield will be reduced slightly. Statewide, I estimate about a 10 percent yield reduction on dryland corn. Irrigated corn that got water early looks much better.
We should be cutting corn in about two weeks. In Louisiana, two problems will reduce yields this year: lack of nitrogen uptake early and midseason drought stress. Crops are resilient and can fool you sometimes, but, corn only 6 feet tall and stressed most of the season will yields less. Corn was so drought-stressed in some areas that it used water from stalks to fill ears.
Louisiana milo acreage was down to 100,000, acres according to the latest USDA estimates. The crop is heading unevenly, which will make harvesting and midge control more difficult. Yield will be reduced slightly because of lack of nitrogen during the early part of the season and extreme drought stress.
The soybean crop has improved tremendously, even in northwest Louisiana. We needed rain over most of the state and we have received it; the soybean crop has excellent yield potential. We have been making some preliminary yield estimates, and the numbers are positive. Most predicted yields have ranged from about 35 to 70 bushels per acre for the crop that will be harvested in the next three weeks.
Although insects and diseases have been relatively quiet this year, we cannot be complacent about them. Almost every field I walked the week of July 18-22 had aerial blight and cercospora leaf blight — not always severe but enough to warrant spraying.
Until the crop is about at R6 (beans in the pod are touching and moisture is around 50 percent), yield losses from insects and diseases can occur. Late in the season, loss of seed quality becomes more of a factor than loss of yield.
Spraying for insects has been minimal. In fact, in the six soybean verification fields we check weekly, we recommended the first insect application for three-cornered alfalfa hoppers in Richland Parish the week of July 18-22. The other five fields have not yet received an insecticide application. The Concordia and East Carroll fields may get by with no insect spray this year.
Orthene or acephate was applied early for stink bugs, and control has been outstanding. We are seeing some slight population increases of stink bugs and other insects. Some limited insecticide applications are being made.
Regarding fungicides, I commend several groups and individuals when it comes to how they have handled the daily barrage of rust rumors and “quasi confirmations.” I am pleased with Louisiana producers, county agents, consultants and other industry personnel who have helped keep the calm in turbulent waters. We are finding soybean rust, confirming it and releasing that information very efficiently.
Most of the Louisiana crop (estimated 60 to 65 percent) was out of danger Friday, July 22. The remaining later-planted crop will need about four to five weeks before it is out of danger. We must scout vigilantly this is the portion of the crop. The LSU AgCenter is not recommending spraying for rust nor spraying any fungicide at R1.
Some confusion remains as to which fungicides work best for which diseases. I am not going to get into the strengths and weaknesses of the compounds, but I recommend improved communication. I have heard of producers applying only triazoles (rust compounds) only over several thousand acres, thinking that these compounds would control cercospera, aerial blight and other pod and stem diseases. This is not true. They will do fine on rust if you have it.
If you have questions about fungicide use and crop cultural practices in general, please call a county agent or a consultant. I struggle with producers making mistakes by spending money worthlessly on something that someone has sold them or just making the wrong decision because of lack of information. If you have questions, call someone. If they do not know the answer, perhaps they will call someone who does. I do it all the time.
David Y. Lanclos is the soybean, corn and grain sorghum specialist at LSU AgCenter. e-mail: [email protected]