Sweet Corn

 IPM Personnel are still capturing low numbers of European corn borer (ECB) moths, although even these captures are fairly sporadic, and extremely low in the northern counties (see map at left).  Despite this, single digit feeding percentages were found on Middlesex county whorl stage corn on Wednesday of this week.  It is likely that ECB injury has occurred on early plantings in most areas, although it is probably very light.  Early plantings grown under plastic will be at risk first, followed by the first bare ground plantings.   Growers should begin scouting whorl corn for injury.

Sweet corn emerging tassel with ECB droppings.
Photo: Kris Holmstrom

Look for the characteristic “shot-hole” type of feeding (photo below at right) and consider treating when infested plants exceed 12% in a 50 plant sample.  As plantings proceed to the pre-tassel stage, ECB larvae may be found in emerging tassels (see photo at left).  It is a good idea to treat individual plantings as they move into the full tassel/first silk stage one time.  This eliminates any ECB larvae that have emerged with the tassels as they begin to move down the stalk to re-enter near developing ears.

Useful insecticides for this particular application include synthetic pyrethroids (IRAC Grp 3), spinosyns (including OMRI approved Entrust) IRAC Grp 5), and diamides such as Coragen (IRAC Grp 28) or materials such as Besiege which include the active ingredient in Coragen.  Synthetic pyrethroids alone should NOT be used for corn earworm (CEW) protection on silking corn.  Control with these materials is very inconsistent.

The highest nightly trap catches of ECB for the week ending 5/29/19 are as follows:

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Sweet Corn

Low numbers of European corn borer (ECB) moths continue to be captured in a few traps (see map at left).  Several cold nights may have suppressed the first flight of the season, although declining ECB populations due to transgenic corn may play a part in the low catches.  Early plantings grown under plastic will be at risk first, followed by the first bare ground plantings.   Through the central counties, a few early corn plantings have reached the whorl stage.  Growers should begin scouting whorl corn for injury.  Look for the characteristic “shot-hole” type of feeding (photo below at right) and consider treating when infested plants exceed 12% in a 50 plant sample.

The highest nightly trap catches of ECB for the week ending 5/21/19 are as follows:

Several corn earworm (CEW) individuals have been captured in blacklight traps this week.  Catches occurred at Port Colden in Warren County, Matawan in Monmouth County and Woodstown in Salem County.  These individuals likely represent a limited overwintered population to our south, and arrived on the southerly breezes that occurred over the weekend and early this week.  There is little threat from these CEW at this time.

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It is extremely important to know which pathogen is causing damping-off problems and which fungicide to properly apply. The key to controlling damping-off is being proactive instead of reactive. Always refer to the fungicide label for crop use, pathogens controlled, and application rates.

Damping-off is caused by a number of important vegetable pathogens and is very common during the spring. Damping-off can kill seedlings before they break the soil line (pre-emergent damping-off) or kill seedlings soon after they emerge (post-emergent damping-off). Common pathogens that cause damping-off include Pythium, Phytophthora, Rhizoctonia and Fusarium spp.

Control of damping-off depends on a number of factors. First, is recognizing the conditions which may be leading to the problem (i.e., weather/greenhouse growing conditions) and second, identifying the pathogen causing the problem.

Conditions Favoring Damping-off

Although all four pathogens are associated with damping-off, the conditions which favor their development are very different. In general, Phytophthora and Pythium are more likely to cause damping-off in cool, wet or overwatered soils that aren’t allowed to dry out due to cloudy weather or cooler temperatures. Conversely, Rhizoctonia and Fusarium are more likely to cause damping-off under warmer, drier conditions especially if plug trays are kept on the dry side to help reduce transplant growth. [Read more…]