Vegetable Crops Edition

Seasonal updates and alerts on insects, diseases, and weeds impacting vegetable crops. New Jersey Commercial Vegetable Production Recommendations updates between annual publication issues are included.
 
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NJ Commercial Vegetable Production Recommendations

Rutgers Weather Forecasting - Meteorological Information important to commercial agriculture.

May 30, 2024

Edema development in brassica crops

Edema is often expressed as off-color swellings or galls that appear on leaves and stems. Edema develops when epidermal cells hold excessive water due to a slowing of evapotransporation when hot, muggy days are followed by cooler, wetter weather. Edema develops because the plant takes in more water (due to a high soil moisture content) faster than it can get rid of it through evapotranspiration causing cells to rupture which results in the blistering of the leaves. Edema is strictly caused by environmental factors and can appear whenever these conditions are met. Properly monitor soil conditions, irrigation cycles, and the weather to avoid over irrigating on warm, hot early spring days, especially when quick cold fronts/temperature drops and cloudy weather are expected.

Symptoms of edema on collard leaf. Note the off-color appearance of leaf surface.

Symptoms of edema on top side of
collard leaf.
Note the off-color appearance of leaf surface.

Edema, bottom side of collard leaf. Note the irregular, 'corky appearance caused bythe rupture of leaf cells.

Edema, bottom side of collard leaf.
Note irregular, “corky” appearance due to leaf cell rupture.

Filed Under: Vegetable Crops Tagged With:
May 29, 2024

Vegetable IPM Update 5/29/24

Sweet Corn

European corn borer (ECB) moth captures have increased in northern and central county light traps.  Numbers are low, as they have been in recent years, and no feeding has been detected on whorl and pre-tassel stage sweet corn as far south as northern Burlington County.  Whorl corn is the primary target for egg laying.  If the peak of the first flight is late, it sometimes results in heavier infestations on 2nd and 3rd plantings than on the first.  Feeding may be present in the southern counties, and should rise over the next 3 weeks.

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 peasts on 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.  It should be noted that Coragen or Vantacor, used alone, are not toxic to bees that may be visiting corn tassels during this stage.  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 5/29/24 are as follows:

Bellemeade   1 Hillsborough   1
Califon   1 Sergeantsville   1
Farmingdale   1 South Branch   1
Georgetown   1

[Read more…]

Filed Under: Organic Production, Vegetable Crops
May 29, 2024

Controlling Phytophthora blight in cucurbit plantings

As the summer heats up in New Jersey, the control of Phytophthora blight in cucurbit plantings can be extremely difficult (even with the use of fungicides) as hot, wet weather finally sets in. Mitigating losses to Phytophthora blight in cucurbit crops begins with long crop rotations,  where recommendations suggest crop rotations longer than 5 years if possible. Other cultural practices include avoid planting in low areas of the field where water may persist after rain or overhead irrigation, rogueing out infected plants as soon as possible, cutting the plastic to help dry out the soil, proper weed control, and proper preventative fungicide programs.

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Filed Under: Vegetable Crops Tagged With: , ,
May 27, 2024

Controlling Septoria Leaf Spot and Bacterial Leaf Blight in Parsley

Septoria leaf spot (SLS) in Parsley can cause significant losses in fields where it has become established. Like other Septoria’s, the leaf spots produced on parsley look much like the leaf spots produced on tomatoes and other crops. Septoria leaf spot overwinters from year to year on infected debris so long crop rotations of 2 or more years are important to help reduce disease pressure. During the season, SLS will spread rapidly with each subsequent rainfall and/or overhead irrigation event. Therefore, early detection and preventative fungicide applications are key to successfully controlling SLS. There have been a few new fungicides labeled for SLS control in the past few years.

Parsley SLS

Septoria leaf spot of Parsley

[Read more…]

Filed Under: Vegetable Crops Tagged With: , ,
May 26, 2024

Diagnosing Verticillium Wilt in Eggplant

Verticillium wilt has been reported in eggplant this summer. It is a common soil-borne fungal pathogen that once it has infested soil can remain for a very long time. Verticillium wilt is caused by either Verticillium albo-atrium or Verticillium dahlia and has a wide host range (over 200 plant species). Both pathogens can survive (overwinter) as microsclerotia in the soil. Verticillium wilt prefers cooler weather and drier soils and can be more severe in neutral to alkaline soils. Solanaceous weeds such as Nightshade may harbor the pathogen. [Read more…]

Filed Under: Vegetable Crops Tagged With: ,
May 25, 2024

Phomopsis fruit rot in eggplant

Phomopsis blight is caused by the fungal pathogen, Phomopsis vexans. It survives between seasons in the soil on infested plant debris. Although the pathogen can infect stems and older leaves, fruit infections are most prominent. Cankers that develop on stems and branches can cause the entire plant to collapse and die. Circular, grayish spots may develop on infected leaves. On fruit, the pathogen causes brownish-black spots that can quickly enlarge causing flat spots that can produce black pycnidia (e.g., fruiting bodies) that produce masses of conidia (spores) which are rain dispersed onto healthy plants and fruit. Phomopsis blight is favored by hot, wet weather (85 – 90 F). Spores germinate in free water on leaves and fruit causing infections. The pathogen can survive on solanaceous weeds such as nightshade, so good weed control is necessary. Crop rotations of 3 to 4 years are recommended. If possible, infected fruit should be harvested and removed from the field to help reduce to inoculum and the spread of the disease. Fields should be scouted on a regular basis, especially fields with a history of Phomopsis blight. Fungicide applications include Quadris Top (difenoconazole + azoxystrobin, 7 +11) or Priaxor (fluxapyroxad + pyraclostrobin, 7 +11) rotated with chlorothalonil every 7 to 10 days. For more information please see the 2024/2025 Mid-Atlantic Commercial Vegetable Production Recommendations Guide.

 

Filed Under: Vegetable Crops Tagged With: , ,