Sweet Corn

European corn borer (ECB) moth catches are very low now.  The first flight is largely over, and as is common, feeding signs in the field have increased as eggs hatch.  Present adult activity is largely confined to Gloucester and parts of surrounding counties (see ECB map).  Larval feeding ranges from single digits to 40% in areas where IPM personnel are operating, although many plantings still have no detectable feeding at all.  The highest feeding percentages are currently in Mercer and parts of Morris counties.  Be sure to begin monitoring plantings for ECB feeding while they are still in the whorl stage.  Consider treating when the number of infested plants in a 50 plant sample exceeds 12%.  Feeding in the whorl stage will appear as numerous small holes (called “shot-hole”) on leaves, with damage present on consecutively younger leaves. As plants progress to pre-tassel and beyond, droppings and  larvae may be found in or on the emerging tassels (see photo at right).  Any planting remaining at or above threshold as it proceeds to full tassel should be treated, as this is the last stage at which ECB larvae will be exposed and vulnerable to insecticidal sprays.    Insecticides that are acceptable in organic production include the spinosyn based material Entrust (IRAC-5) and Dipel (IRAC-11a).  The 10G formulation of Dipel is particularly useful when granules can be dropped or broadcast such that they get into the whorls of corn plants.  Other effective insecticides include Coragen (IRAC 28), and the synthetic pyrethroids (IRAC 3).  See the 2016 Commercial Vegetable Recommendations Guide for a more complete list of insecticides.  [Read more…]

• Cucurbit downy mildew has been reported on cucumber as far north as northern North Carolina this past week. CDM was reported on acorn, yellow summer, and butternut squash in South Carolina and on watermelon and cucumber in North Carolina. All cucurbit growers should scout on a regular basis for downy mildew and powdery mildew.
• There have been no new reports on late light in the region. Late blight (US23) was reported on potato on the Eastern Shore a few weeks ago. All tomato and potato growers in the region should scout on a regular basis.
• Blackleg caused by Dickeya dianthicola has been reported in potato this past week. All potato growers should continue to scout for symptoms of Blackleg, especially as temperatures warm up, and report any suspect plants or fields for testing.

• There have been no new reports on late light in the region. Late blight (US23) was reported on potato on the Eastern Shore two weeks ago. All tomato and potato growers in the region should scout on a regular basis.
• Blackleg caused by Dickeya has been reported in potato this past week.
• Cucurbit downy mildew has been reported on cucumber as far north as central North Carolina this past week. CDM was reported on acorn, yellow summer, and butternut squash in South Carolina on 6/14. All cucurbit growers should scout on a regular basis for downy mildew and powdery mildew.

Sweet Corn

Catches of European corn borer (ECB) have declined through much of the state.  Remaining areas of highest activity include parts of Monmouth, Mercer and Salem counties (see ECB map).  ECB infestations are now rising in sweet corn plantings, but are well below normal levels.   Feeding ranges from single digits to 20% in areas where IPM personnel are operating, but many plantings have no detectable feeding at all.  Be sure to begin monitoring plantings for ECB feeding while they are still in the whorl stage.  Consider treating when the number of infested plants in a 50 plant sample exceeds 12%.  Feeding in the whorl stage will appear as numerous small holes (called “shot-hole”) on leaves, with damage present on consecutively younger leaves. As plants progress to pre-tassel and beyond, the actual larvae may be found in or on the emerging tassels (see photo).  Any planting remaining at or above threshold as it proceeds to full tassel should be treated, as this is the last stage at which ECB larvae will be exposed and vulnerable to insecticidal sprays. Often, early sweet corn plantings suffer from “split set”, in which germination does not occur in a uniform

Sweet corn tassel with ECB larvae.
Photo: Kris Holmstrom

fashion. The result is a planting where all plants do not reach full tassel at the same time.  This situation may require an extra tassel spray if there are several days difference in the time full tassel is reached on a significant number of the plants.  Insecticides that are acceptable in organic production include the spinosyn based material Entrust (IRAC-5) and Dipel (IRAC-11a).  The 10G formulation of Dipel is particularly useful when granules can be dropped or broadcast such that they get into the whorls of corn plants.  See the 2016 Commercial Vegetable Recommendations Guide for more insecticide choices.

The highest nightly ECB catches for the previous week are as follows:

  [Read more…]

Sweet Corn

European corn borer (ECB) adult catches have declined, and are now quite low throughout the state.   The most consistent catches at this time range from southwestern Burlington County through Cumberland County (see ECB map).  The earliest sweet corn plantings are now silking in southern NJ, and are approaching full tassel in some northern sites.  Feeding percentages are still very low (to 4% in central counties), but growers should expect that eggs are now hatching, and larval infestations could appear on all corn whorl stage and older.  Be sure to begin monitoring the earliest plantings for ECB feeding while they are still in the whorl stage. Consider treating when the [Read more…]