Radio advertisements, email blasts, and other media are warning of corn diseases and the need for fungicides. Two months of humid, wet weather has allowed for disease development. It’s important to know what diseases truly are in your field before spraying a fungicide, particularly with today’s economics. Here’s what we’re seeing in fields right now in the Clay, Nuckolls, Thayer, Adams county area. Based on the diseases we’re seeing, we would recommend you scout your fields to know whether you have mostly bacterial or fungal diseases present. Consider disease pressure, where on the plant the disease is occurring, growth stage, and economics. We have had southern rust show up in 10 of the last 11 years I’ve been serving in this area. If you spray a fungicide at tassel, you may not have enough residual to ward off southern rust when it appears later, potentially resulting in the need for a second application. In our area thus far, I’m not seeing enough disease pressure in many fields to warrant a fungicide at tassel; consider delaying an application till later for economic and resistance-management reasons. Ultimately this decision needs to be done on a field by field basis. Please also see this UNL CropWatch article regarding fungicide application and corn growth stage. Although I don’t have a photo of it, I’ve also seen common rust in the mid and lower portions of corn canopies thus far.
Happy New Year! Wishing all of you and your families a wonderful 2015! As I look back at 2014, there are several ag-related observations that I noted throughout the year.
The first observation continues to be the way communities and people in this County/area pull together in difficult times. Whether after tornadoes/wind storms or helping other farm families who had an injured family member or had lost a family member, it’s just a blessing to see the way people pull together to help each other in time of need. It was also a blessing for many who were unable to harvest in 2013 due to the August 1st storm, to harvest fields in 2014, and for many in the area to experience really good irrigated and dryland yields this year.
The dry winter of 2013/14 allowed for very mellow ground during planting time. Often seeding depth ended up ½-1” deeper than intended. The dry winter also didn’t allow for good residue decomposition leading to problems during planting and ensuing stand emergence. Cutting off residue and high rains in May led to unintended consequences of replant situations when residue was moved off of farmers’ fields onto neighboring fields, suffocating emerged plants in portions of fields. I’m not sure what the solution is for the future other than it really needs to be something worked out with neighboring farmers, but perhaps mentioning it here opens an opportunity for future conversations.
Cover crops have been incorporated into more operations in recent years, yet the ultimate goal for using them remains important in determining what species/crops are used in the fields. We also realized the importance of determining amount grazed prior to turning cattle into fields (whether for grazing cover crops or crop residue), as high winds in winter 2013/14 in overgrazed fields led to soil blowing throughout the winter.
The May frost showed us emerged soybeans at the cotyledon stage held up well to the frost compared to the corn. We also again watched Goss’ wilt show up systemically by 6 leaf corn that was injured early by frost or hail in fields where Goss’ wilt had been a problem in the past. We need more research/understanding of this disease. Wheat continues to show us its resiliency as it winterkilled in portions of fields, withstood drought-stress, and then made up yield in the last 4-6 weeks.
Perfect pollination conditions coupled with high solar radiation, low night-time temperatures, and timely rain events were keys to the bountiful corn crop we experienced this year. Soybeans were more of a mixed bag. In walking fields and in conversations with farmers, I think the disappointment in some irrigated yields could be attributed to early/over-irrigation, disease problems, and planting date. UNL on-farm research showed on average a 3 bu/ac yield increase when soybeans were planted in late April to first week of May (regardless if growing season was warm/dry or cold/wet like it was this year) and those I’ve talked to who achieved 80+ bu/ac in the area this year planted in that time-frame. I’m curious if there’s something to planting a 2.4-2.5 maturity early vs. a 3.0+ maturity early as some area producers are seeing strong yields from a shorter season hybrid planted early the past few years. So if you’ve also seen this and/or are interested, that will be an on-farm research project to try next year. Please let me know if you’re interested!
Here’s wishing you a healthy and prosperous 2015!
Fair week tends to be time for tasseling in corn and considerations for watering and fungicide application are being made. Regarding diseases in corn, there has been confusion about a few diseases, particularly about a disease called physoderma brown spot which some have confused for southern rust. The fungus causing physoderma brown spot feeds on pollen and debris on leaves and does not cause harm to the corn plants themselves. Because the spores of this fungus move via water (it’s closely related to oomycetes), numerous lesions can appear on leaves in bands or areas where water collects. While the lesions may look like early southern rust, there will be no pustules present and often purple colored lesions will also be observed in the midrib, leaf sheath, stalk, and outer husks.
When differentiating between southern rust vs. common rust, there are several criteria to consider and this NebGuide is a great resource. Typically common rust will have brick-red pustules randomly scattered on the upper and lower leaf surfaces that are larger in size. It is common rust that we are currently seeing in our fields.
Southern rust in our area tends to have very small, raised, tan-orange pustules on the upper leaf surface of leaves in localized areas on mid-upper leaves. These pustules are tightly clustered on the leaves. However, color and size are relative as sometimes the two diseases can look alike. Microscopic observation is the best way to differentiate the two diseases. Fungal spores from Puccinia sorghi causing common rust will be near perfect round circles whereas fungal spores fromPuccinia polysora will be oblong in shape.
have a bacterial leaf blight that is affecting quite a bit of leaf tissue on some hybrids. These lesions are long and skinny appearing at first to be limited to the veins. There’s been concern about these lesions being severe gray leaf spot but it’s not and there’s nothing you can do about the bacterial disease. Please don’t mistake this bacterial disease as a fungal one and trigger a fungicide application too early.
Fungicide Application Timing
We tend to see southern rust in our part of the State each year; it’s a matter of time. Triggering a fungicide application too early may result in no residual for when you need it if/when southern rust occurs. Every year some producers make more than one fungicide application due to blanket applications at tassel or shortly after followed by another fungicide application when southern rust occurs later in the year. Consider good fungal resistance management and apply fungicides when disease pressure warrants them in your fields and also consider economics for your situation for proper fungicide application timing.