Rutgers Cooperative Extension
The Plant & Pest Advisory serves NJ growers by reporting on important pests and recommending responses that are grounded in reproducible trials.
Articles in this section contain information helpful to the NJ commercial organic grower.
Sharing organic practice trial results between land-grant universities is a cost effective way to create a common knowledge base built on the strengths of individual programs. In the sidebar, find institutions with programs in organic agriculture which augment knowledge developed at the Rutgers New Jersey Ag Experiment Station.
Rutgers Cooperative Extension Field Guides: These concise guides help with decision making from pre-planting to harvest. For each crop listed, learn what pests to proactively look for as the season progresses, how to look for them, and when to take action.
Sweet Corn
European corn borer (ECB) moth catches continue to be extremely low around the state. We are in between adult generations at this time. ECB population maps will resume if second flight catches rise to high enough numbers.
The highest nightly trap catches of ECB for the week ending 07/20/22 are as follows:
| Allentown 1 | Old Bridge 1 |
| Dayton 1 | Sergeantsville 1 |
| Hillsborough 1 | South Branch 1 |
With high temperatures this week and predicted for next week, there are concerns about pollination of pumpkin and other crops. Flower bud abortion can occur if temperatures are in the high 70’s at night or in high 90’s during the day for several consecutive days. Heat stress causes other issues with plant functions and plant health. However, for crops that need pollination, it is especially stressful when hot and dry weather conditions occur.
Honeybees, bumblebees, squash bees, and many other solitary bees will pollinate pumpkin flowers. Pumpkin flowers only live a few hours after blooming and then go limp and close. Therefore, they must be pollinated during the brief window when they are open. It is important to keep adequate soil moisture during pollination to help foster flower health, pollen quality, and good pollen acceptance by the stigma. Pollination cannot occur if the buds and flowers don’t form properly. Irrigation is recommended, as well as other plant health maintenance practices to keep pumpkin roots, vines, flowers and fruit growing properly during this heat wave and throughout the season.
Some other factors to consider in the future to ensure adequate pollination include:
1. Keep plant populations at recommended rates to not have excessive foliage. The nice thing about pumpkin vines is once they cover the ground, they make for good weed competition. However, too much leaf cover and high plant densities can hinder pollinators from locating flowers under the canopy. Additionally, too much foliage causes plants to remain wet for longer periods of time, encouraging fungal diseases.
2. Do not rely solely on native bee populations and investigate hive rentals to accentuate populations of pollinators.
3. Excessive plant growth in response to higher-than-recommended nitrogen applications can also delay flowering and fruit set. Therefore, do not over-fertilize pumpkins. This is true for all growth stages, but especially before fruit set.
4. Besides poor plant/flower quality, drought can lead to a higher than normal male/female flower ratio, resulting fewer pumpkins per plant.
For more information about pollination see the 2022/2023 Mid-Atlantic Commercial Vegetable Recommendations pages 27-33.
Sweet Corn
European corn borer (ECB) moth catches continue to be extremely low around the state. We are in between adult generations at this time. ECB population maps will resume if second flight catches rise to high enough numbers.
The highest nightly trap catches of ECB for the week ending 07/13/22 are as follows:
| Hillsborough 1 | Port Murray 1 |
| Milford 1 | Sergeantsville 1 |
| Milltown 1 | South Branch 1 |
| Oldwick 1 |
Sweet Corn
Note: No trap data from the southern counties is available this week, so maps will not appear in this edition.
European corn borer (ECB) moths remain a sporadic, low component of blacklight trap catches. Feeding in pre-tassel stage is still present in some areas, but is now less common. ECB injury over the threshold of 12% of plants infested, while still around, has been declining.
Growers should still examine plantings in whorl or pre-tassel stages for signs of ECB 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. 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 or Vantacor (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. [Read more…]
For over a decade, basil downy mildew (BDM) has caused significant losses in basil grown in organic and conventional field and greenhouse production across the United States. At the time of its introduction, there were very few fungicides labeled for its control making it nearly impossible to grow a successful crop in many areas of the country. [Read more…]
Sweet Corn
Low numbers of European corn borer (ECB) moths remain a sporadic, low component of blacklight trap catches. Feeding in whorl and pre-tassel stage is now less common, as control has been applied to infested plantings and later blocks (now in whorl stage) have avoided most of the egg laying period. Slightly higher adult activity is in scattered pockets around the state (see map below at right). ECB injury over the threshold of 12% of plants infested, while still around, has generally been declining over this past week. We expect feeding wind down over the next week or so as we move into the period between generations.
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 or Vantacor (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 6/29/22 are as follows:
| Bellemeade 1 | Farmingdale 1 | Morristown 1 |
| Blairstown 1 | Georgetown 1 | New Egypt 1 |
| Centerton 1 | Lawrenceville 1 | Princeton 1 |
| Crosswicks 1 | Matawan 1 | Sergeantsville 1 |
