Nutrients

Sulfur Deficiency in Corn and Watermelon

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).

Normally at this time of year, I’d be writing about how bad yellow shoulders and other fruit ripening problems are in Maryland tomatoes. But this has been a strange season with May weather in March and March weather in May, which caused a great deal of catfacing problems this year. However, except for a few fields in a few places there have been far fewer troubles with tomato yellow shoulders or fruit ripening problems than we normally see this time of year—at least for now. Why is this?

Vegetables have a relatively high nitrogen requirement and at times growers apply too much fertilizer-N that contributes to ground and surface water pollution. Fertilization can be made more efficient by plant analysis. Plant tissue (petiole) nitrate testing is a way of monitoring the nitrogen condition of the crop during the growing season. This is an especially useful method as the petiole is a very good indicator of current N supply and management practices such as fertigation allow for corrective measures when deficiencies are found.

Over the last few months in our area there have appeared problems with tomato ripening. The ripening problems are called various names such as blotchy ripening, yellow shoulder, grey wall, internal whitening, etc. (fig 1).

Tomato Ripening Problems and the Role of Potassium

Nutrient Problems and Their Management in Tomatoes

Growers may already be seeing leaf symptoms on their cantaloupe plants that are often misdiagnosed as a foliar disease. However, these leaf symptoms described below indicate manganese (Mn) toxicity which is related to low soil pH.

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.

Using Nitrate-N Petiole Sap -Testing for Better Nitrogen Management in Vegetable Crops