More potassium deficiency and leaf striping in corn

This information was summarized from a June 19 teleconference with ISU Extension field specialists in crops.

  • Typical rainfall amounts of 2 to 4 inches were reported in most areas. Some locations received heavy rains of up to 11 inches. Wind damage and erosion were reported with the heavy rainfall. Counties in south central, southwestern, and west central Iowa are still dry.
  • Crops in general are improving with the moisture received. Corn is growing rapidly; typically at the V8 to V10 growth stage. Most soybean plants are at the V4 to R1 growth stage and in some areas growth has been slow because of cool temperatures, weed competition, and herbicide damage.
  • Stewart's disease is still showing up in cornfields statewide, but seems to be more common in southern counties. In these fields, scattered waist-high corn plants have wilted whorls and rotting growing points.
  • More potassium deficiency symptoms in corn were reported statewide. Causes of potassium deficiency may include dry soils, compaction, planting depth, poor aeration, and poor nodal root development. Other corn leaf striping symptoms were reported that seem to be caused by something other than Stewart's disease or potassium deficiency.
  • Very low numbers of first-generation European corn borer larvae and egg masses were reported. Stalk borers were reported in a few fields.
  • Second cut alfalfa harvest has begun in southern and central Iowa. Potato leafhoppers are not at economic levels at this time. Alfalfa regrowth is being slowed by adult alfalfa weevils in southwestern and west central areas.
  • The oat crop ranges from being headed out to starting to ripen and turn color in southern Iowa.
  • Pastures are still short in the dryer areas of the state. Musk thistle, Canada thistle, and multiflora rose are blooming.

This article originally appeared on page 115 of the IC-484(15) -- June 26, 2000 issue.

Updated 06/25/2000 - 1:00pm