Respone to Fungicide
As corn acres start tasseling over the next few weeks, one of the last majo r decisions in corn production has to be made: should I spray a fungicide? Whether it’s the heavy rains, late planting, fast early growth with hot temperatures, or early signs of foliar diseases, there’s a lot of factors to consider making the right decision!
A 230-bushel corn crop accumulates about 9,000 lbs./acre of dry matter when it hits VT/R1. At black layer or R6, 50-60 days later, that same acre will accumulate ~20,000 lbs./acre of dry matter. Consider this:
An acre of corn is going to double its dry matter and sequester most all the photosynthate it takes to fill the ear during this 60-day window and will do it without putting on any new leaves. How important do you think it is to make sure leaves are protected and actively photosynthesizing?
Final corn yield depends on the number of kernels that develop and fill. R3 stage (milk) occurs about 18 days after silking, and signals rapid starch accumulation as sugars produced in photosynthesis travel to the kernel and are converted into starch.
Looking at an individual corn kernel, the endosperm is about 82% of the kernel’s dry weight. The endosperm is packed with starches. The starch is produced from carbohydrates cr eated from photosynthesis in leaves. About 75% of those carbohydrates will be produced from ear leaf and above, and 25% from below the ear leaf. Corn plants can redirect carbohydrates produced in photosynthesis to fill the developing kernels, but if too many carbohydrates need be removed from the stalk, leaves, and roots instead of concurrent photosynthesis, it can weaken the plant itself, and remove the natural defense mechanisms that are protecting the plant from disease infection.
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