36 Like Us on Facebook: BetterFarmingON Better Farming | January 2024 crops: yield matter$ MYCOTOXINS IN CORN FOR 2023 Learn how to protect your yield from this disease. By Dale Cowan The 2023 cropping year was full of environmental challenges with a wide range in rainfall amounts, with some areas receiving four times the normal amount across Ontario. The accumulation of crop heat units started slow in May and never really caught up until well into October. Corn black layer typically occurs in mid- to late September and some fields in 2023 black-layered in the third week of October. This contributed to high kernel moistures and slow dry down leading to a delayed harvest. Persistent rainfall during the tassel emergence and early silking period led to conditions conducive to the development of Gibberella ear rot and subsequent production of the mycotoxin DON. As harvest was delayed, it became evident through testing corn with visible signs of Gibberella ear rot that higher levels of DON were present. End users of corn contract for No. 2 yellow corn with very low to no DON. As a result, discounts were put in place to encourage delivery of clean corn. Commercial elevators had no choice but to follow the discount schedules. The elevator system is the middle link in a supply chain between farmers and end users. In Ontario, over 55 per cent of the grain-handling facilities are on-farm, owned by farmers. Some facilities are of the size to rival any commercial system. This gives the farmer more marketing and delivery options to end users. However, they are not immune to the discount schedules. Let’s look at discount schedules in 2023. Below is the DON discount schedule and appropriate discounts applied based on DON level, yield and corn at $6 per bushel. High DON values are a substantial reduction in income. Clearly, higher yields lessen the impact. There are differences in hybrids and equally there are environmental conditions that favour disease development of Gibberella ear rot. We have examples of where the same hybrids were planted near one another; one had elevated DON levels and the other location was clean. This is frustrating for everyone in the industry; the weather conditions at the time of silk emergence, and for three to four weeks after, impact the incidence and the severity of Gibberella ear rot, and subsequent development of the mycotoxin DON. Gibberella ear rot is often associated with high yield environments. So are fungal leaf diseases such as northern corn leaf blight (NCLB) and tar spot. High yield environments have dense canopies that keep the foliage more wet for longer into the day, fostering an ideal environment for fungal growth. The chart on the following page from our elevator system indicates the distribution of DON tests in 2023. The majority of tests are in a range that avoids any major discounts. The last major year of significant DON levels was 2018. We can see a different distribution of DON levels with fewer low-testing samples and a shift to the higher test levels. This was indicative of a very wet period that persisted throughout the grain fill period well into harvest. Some on-farm samples are not included in this data set, so the results are a bit misleading. I do recall some fields Tar spot on corn. Dale Cowan photo Gross revenue after DON discounts $6 per bushel selling price 180 200 220 230 240 $0.00/bus DON discount DON ppm <3 3.1 to 4.0 4.1 to 5 5.1 to 6 6.1 to 7 7 to 8 0 .25 0.51 0.76 1.02 1.52 $1,080.00 $1,035.00 $988.20 $943.20 $896.40 $806.40 $1,200.00 $1,150.00 $1,098.00 $1,048.00 $996.00 $896.00 $1,320.00 $1,265.00 $1,207.80 $1,152.80 $1,095.60 $985.60 $1,380.00 $1,322.50 $1,262.70 $1,205.20 $1,145.40 $1,030.40 $1,440.00 $1,380.00 $1,317.60 $1,257.60 $1,195.20 $1,075.20 Yield Bus / acre
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