Sweet Corn

Tar spot of corn has been confirmed in Maryland for the 2023 growing season. The first report came from a field in Cecil county, followed by several additional reports in Harford and Carroll county.

All eyes have been on news headlines coming from the Black Sea for the last two to three weeks since the termination of the previous agreement between Russia and Ukraine. The escalation in the war between these two nations has seen drone strikes, missile engagements, and major destruction of Black Sea ports like Odessa in Ukraine. Traders have watched these headlines and acted accordingly in the market place as the price of corn and wheat retraced previous months losses.

Tar spot in corn, Tar spot is a foliar disease of corn caused by the fungus Phyllachora maydis. This disease has the potential to significantly impact yield.

When selecting sweet corn seed varieties this year, you may want to consider selecting some of the genetically modified Bt hybrids that have built-in resistance to different insect pests. Bt sweet corn varieties have been genetically engineered with genes from the bacterium Bacillus thuringiensis (aka “Bt”), which produce proteins that are toxic to different insect pests.

For the last couple of years, I have talked about and conducted research on sulfur (S) deficiencies in watermelon. At several meetings I was asked if the deficiency also appears in (field) corn. I could only relate the comments I have heard from several corn growers that they have often found their corn crop to be low or deficient in sulfur. I bring all this up again because I have seen several sweet corn fields lately that have sulfur deficiencies (fig 1).

Fruit and Vegetable News, Volume 12, Issue 6 (September 9, 2021)

Fruit and Vegetable News, Volume 12, Issue 4 (July 15, 2021)

In the last few weeks several sweet corn fields as well as some watermelon and even a few tomato fields have been found with sulfur deficiencies (figs. 1 and 2). In sweet corn symptoms often appear as green leaves with light yellow or green striping on the newer leaves (fig. 1). In watermelon symptoms appear as a light green or light yellowing of the leaves of newer growth (fig. 2). In tomato unless severe you usually do not see any visible sulfur deficiency symptoms in the field, but fruit set and quality could be worse

I have seen several sweet corn fields lately that have sulfur deficiencies (fig 1). One of the possible reasons we are seeing more S deficiency is because less sulfur is being deposited into the soil from the atmosphere due to reductions in acid rain. In 1986 about 24 lbs/a of sulfate were deposited in Maryland soils per year, however in 2011 it was closer to just 8 lbs/a each year. Organic matter supplies most of the sulfur to the crop, but sulfur must be mineralized to sulfate-S to be taken up by crop plants.

Current corn earworm pheromone trap captures in Maryland and Delaware and pest management recommendations.