Organic Farm Advisory

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.

Field Guide List

July 19, 2023

Vegetable IPM Update 7/19/23

Sweet Corn

Fall armyworm (FAW) has begun to appear in coastal areas.  We have low level infestations of this pest in whorl stage sweet corn in Monmouth County, and reports of early populations in Cape May, where FAW was a significant problem last season.  This pest is capable of significant injury to sweet corn plants, resulting in severe stunting and failure to produce viable ears.  Importantly, FAW favors whorl, and even seedling stage sweet corn for egg laying so it is critical that growers check even recently emerged plantings for signs of FAW injury.

Infected plantInfected plantNewly hatched FAW larvae cause holes and scratches on leaves that are similar to European corn borer (ECB) feeding, except that they tend to be more concentrated and always lead down into the whorl  (see photos at left).  As the larvae grow, the feeding becomes more destructive, with large ragged holes and obvious droppings deposited in the whorl (see photo at right).  Infected plant

We will provide updates on new FAW appearances and severity as reports come in.  FAW are resistant to synthetic pyrethroids.  Effective sprays should include IRAC grp. 5 (spinosyns) or IRAC grp. 28 (diamides).  The carbamate (IRAC grp. 1A) Lannate is also still effective.  Sufficient water should be used in the applications to allow the solution to penetrate the layer of droppings that may have formed above the caterpillar.

 

European corn borer (ECB) moth activity remains extremely low in areas where blacklight traps are operating in the northern and central counties.  Many plantings exhibiting no ECB injury at all.  We will report on ECB activity should numbers rebound to potentially damaging levels during the second flight.  In recent years, this later flight has not required targeted control in sweet corn.

[Read more…]

Filed Under: Organic Production, Vegetable Crops
July 14, 2023

What Can Summer Cover Crops Do for Soil Health and Future Crops?

Plants floweringNow that some of our spring planted crops have finished, rather than leaving fields fallow or replanting fields that may have had some issues with plant diseases or insect pests, consider replanting with a summer cover crop. It is not too late to take advantage of summer cover crop benefits. What do summer cover crops do for soil health or future crop improvements? See below:

1. Increase Soil Organic Matter– One of the best attributes of having organic matter in the soil is improvement in soil structure. Adding organic matter improves tilth, water infiltration, water holding capacity, nutrient holding capacity and reduction of soil crusting. Also, as important is the increase in beneficial soil microbes and earthworms. Beneficial microbes can compete with pathogens and help release nutrients. Earthworms can cycle nutrients and improve pore spaces in the soil.
2. Reduce Soil Erosion – Just like with winter cover crops, summer cover crops can also reduce wind and water erosion in fields, especially those with slopes. During summer rainfall events, that can be significant if resulting from tropical storms, runoff may not just include soil loss, but also fertilizer and chemical movement. Therefore, keeping cover on a field during non-production times in any season is an excellent practice.
3. Nitrogen Cycling in the Soil – Nitrogen is often the most limiting nutrient for crop production, since it is so readily lost through nitrification and leaching. Storing nitrogen through plant cycling is an excellent way to improve fertility management. Whether it is a grass or non-leguminous cover crops N is still kept in the mix by the cover crop taking up residual N that wouldPerson holding plant to show root system otherwise be lost. The cover crop plant takes up the nitrogen and after the crop is incorporated it decomposes, thus releasing the N for subsequent crops to use. If legume cover crops are planted, they have the ability to “fix” nitrogen from the atmosphere and through the same decomposition process will provide N for subsequent crops. Be sure to inoculate legume seed just prior to planting with Rhizobium bacteria in order to gain the maximum N fixation benefits.
4. Reduce Weeds – When fields are left fallow after crops are harvested, weed growth can occur. If left to produce seeds, these weeds will multiply in subsequent crops. Therefore, managing the field by planting cover crops between cash crops is a great weed management option. As the cover crop grows, it will suppress the germination and growth of weeds through competition and shading. Some cover crop species can also suppress weeds biochemically, either while they are growing or while they are decomposing, which may prevent the germination or growth of other plants (allelopathy). Research has shown some cover crops like wheat, barley, oats, rye, sorghum, and sudangrass may suppress weeds. In some cases, it has also been reported that residues and leachates from crimson clover, hairy vetch, and other legumes have shown weed suppression.
5. Impacts on Plant Diseases – Cover crop residues could possibly be beneficial when it comes to plant pathogens, or can in some cases increase plant disease organisms. Some cover crop species are in the same plant families as cash crops and may be susceptible to the same disease organisms. Therefore, carrying the pathogen to the next crop. This is why paying attention to crop rotations is so important. In other cases, the cover crop residue can improve soil health in order to produce a better environment for beneficial microbes. By improving soil health, water infiltration, air pore space and other positive attributes, some soil pathogens may not survive as well, as in the case of water molds and water fungi. Some cover crops, like sorghum-sudangrass and sunnhemp, have been reported to reduce nematodes in soils. There are multiple positive factors from cover crops that can combat plant diseases.
6. Impacts on Insects – Like with plant diseases, cover crops can be susceptible to the same insect pests as cash crops. However, they may also attract beneficial insects into an area. Insect pests should be monitored in cover crops, just like in cash crops in order to not let populations get out of control and then move into nearby fields after the cover crop is killed.

For more resources on the us e of cover crops check out these resources: Cover Crops for Sustainable Crop Rotations – SARE

Filed Under: Commercial Ag Updates, Field, Forage & Livestock, Fruit, Organic Production, Strawberry, Uncategorized, Vegetable Crops Tagged With: , ,
July 12, 2023

Vegetable IPM Update 7/12/23

Sweet Corn

European corn borer (ECB) moth activity remains extremely low in areas where blacklight traps are operating in the northern and central counties.  Feeding in whorl and pre-tassel stage corn has decreased over the past week.  Many plantings exhibiting no ECB injury at all.    While ECB has become something of a local phenomenon in NJ, growers should not assume that feeding is below economic levels in their area.

emerging tasselsLook 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 small holes in a leafpyrethroids (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 7/12/23 are as follows:

Bellemeade   1 Pennington   1
Hillsborough   1 South Branch   1
Morristown   1

[Read more…]

Filed Under: Organic Production, Vegetable Crops
July 7, 2023

Monitor for Thrips in Vegetable Crops

Now that spring grains like wheat and rye have dried down and are being combined, thrips in those fields will move to vegetable crops, especially when small grains are adjacent to vegetable fields. Thrips are very small and often missed if casually looking at a plant since they hide in blossoms, under sepals, on under sides of leaves and other protected areas on the stems, leaves and flowers. To scout for thrips look at plant parts mentioned above. It is also important to dissect a flower, pulling back petals and sepals to find hiding thrips. It is difficult to see thrips with the naked eye. Therefore, the use of a hand lens will help.

Most adult thrips are elongate, slender, very small (less than 1/20 inch long), and have long fringes on the margins of both pairs of their long, narrow wings. Immature thrips (called larvae or nymphs) are oblong or slender and elongate and lack wings. Most thrips range in color from translucent white or yellowish to dark brown or black. See the photo of an adult thrips below by Dr. David Kerns, Professor, IPM Coordinator and Extension Specialist, Texas A&M AgriLife Extension, College Station.Thrip

Thrips hatch from an egg and develop through two actively feeding larval stages and two nonfeeding stages, the prepupa and pupa, before becoming an adult. Late-instar larvae change in appearance and behavior and are called prepupae and pupae, even though thrips do not have a true pupal stage.

Females of most plant-feeding species lay their elongate, cylindrical to kidney-shaped eggs on or into leaves, buds, or other locations where larvae feed. Thrips have several generations (up to about eight) a year. When the weather is warm, the life cycle from egg to adult may be completed in as short a time as 2 weeks.

Thrips will feed on most all vegetable crops – solanaceous crops like eggplant, tomatoes, peppers, white potatoes, cucurbit crops like cucumber, squash and melons, bean crops, allium crops like onions, garlic and leeks and others.

Thrips feeding on plants can damage fruit, leaves, and shoots and very noticeably affect plants’ appearance. Leaves may be speckled on the top surface from feeding on under sides of leaves by the insect’s sucking mouthparts. Damage to fruit, like tomatoes may not appear until fruit ripen and can be seen as gold flecks on red tomato fruit. For many thrips species, by the time their damage is seen, such as after flowers open or fruit forms, the thrips may no longer be present.

Once thrips are identified, control can be difficult when they are found in high numbers. Preventative measures like the use of row covers and reflective mulch have some success. Both conventional and organic insecticides labeled for thrips control can be found in the Rutgers Commercial Vegetable Production Recommendations guide under the sections for individual vegetable crops. Always read the pesticide label for instructions, safety precautions, application rates and restrictions. Since thrips hide in tight areas of plant parts it is important to have good coverage and penetration when applying insecticides to reduce the population of this hard to control pest.

For more detailed information about thrips see the Rutgers Fact Sheet https://njaes.rutgers.edu/pubs/publication.php?pid=FS291

Filed Under: Organic Production, Vegetable Crops Tagged With: ,
July 6, 2023

Controlling basil downy mildew in the field in 2023

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…]

Filed Under: Organic Production, Vegetable Crops Tagged With:
July 5, 2023

Vegetable IPM Update 7/05/23

Sweet Corn

European corn borer (ECB) moth activity is extremely low in areas where blacklight traps are operating in the northern and central counties.  Feeding in whorl and pre-tassel stage corn has increased slightly over the past week, but only in a few areas.  Many plantings exhibiting no ECB injury at all.    While ECB has become something of a local phenomenon in NJ, growers should not assume that feeding is below economic levels in their area.

European corn borerLook 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 European corn borerpyrethroids (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 7/05/23 are as follows:

Allentown   1 Hillsborough   1
Asbury   1 Milford   1
Bellemeade   1 Lawrenceville   1

[Read more…]

Filed Under: Organic Production, Vegetable Crops