Combat Tar Spot in #Grow24 

If you’re from the Midwest, this won’t be the first article you’ve read about Tar Spot. The foliar disease, caused by the fungus Phyllachora Maydis that has emerged as a significant threat to corn production in parts of the U.S. and Canada over the past half-decade.

The disease is characterized by the appearance of small, raised black spots that resemble specks of tar scattered across the upper and lower surfaces of corn leaves, stalks, and husks. These small, raised black spots are fungal fruiting structures called stromata or ascomata that contain thousands of spores. Under favorable environmental conditions, these spores are released and spread by wind and rain to cause new infections on nearby corn plants.

Tar spot can spread very rapidly when temperatures are cool (60-70°F), humidity is high (>75%), and leaf wetness periods exceed 7 hours per night.

Tar Spot can have devastating impacts on susceptible corn hybrids when the disease develops early and weather conditions remain conducive. The fungus colonizes leaf tissue and disrupts photosynthesis, leading to reduced grain fill. Severe infections can cause premature leaf senescence, poor kernel development, and lower test weights.

Yield losses from tar spot can be highly variable depending on the timing of disease onset, hybrid susceptibility, and environmental conditions. However, in severe cases, losses of 30-50 bushels per acre or more have been documented in the Midwest. The disease can also increase the risk of stalk lodging and reduce corn silage quality.

Since tar spot is still a relatively new disease in the U.S., best management practices are still being developed. Selecting hybrids with better tolerance, applying effective fungicides, reducing residue, and rotating crops will help mitigate the spread of the disease and losses.

#SeeTheDifference With Concept AgriTek 

With a plant and soil health platform built on agronomy, biology and chemistry, Concept AgriTek has been at the forefront of the battle with Tar Spot. Plant and soil health, along with agronomic management have proven to be amongst the greatest tools in the fight.

Products like Residue RX, a product that helps to break down the cell walls of the residue left in the field reduces the amount of crop residue and corn stalk fodder for the fungus to overwinter in. Additionally, Bio Health has show tremendous results in helping to fend off in-season disease and pest stressors.

Figure 1 Bio Health keeps plants healthy to fend off the stressors that negatively impact plant performance and yield. The corn leaves on the bottom were not treated with Bio Health and clearly show the presence of Tar Spot. Plants on top were treated with Bio Health and show no signs of Tar Spot infection.

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