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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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August 2, 2023

Vegetable IPM Update 8/02/23

Sweet Corn

Occurrences of Fall armyworm (FAW) injury are becoming more common, with infestations discovered as far north as Warren County this week.  Some infestations in whorl corn are in excess of 20%.  It is likely that economic infestations are present in much of southern New Jersey now, and could occur anywhere.  Growers are advised to check whorl and seedling stage corn plantings weekly for signs of FAW.  Consider treating if infestation rates exceed 10%.  This pest is capable of significant injury to sweet corn plants, resulting in severe stunting and failure to produce viable ears.

Newly 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). 

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 29, 2023

Vegetable Disease Update: 07-29-23

Filed Under: Vegetable Crops Tagged With: , , , ,
July 28, 2023

Understanding and controlling Rhizoctonia root rot

Even though much of New Jersey has had wet weather recently, which is more favorable to Pythium and Phytophthora development, Rhizoctonia root rot has been reported over the past few weeks in a number of crops. Rhizoctonia root rot, caused by Rhizoctonia solani, is an important soil-borne fungal pathogen with a very large host range. The pathogen can survive saprophytically on living or dead plant material (organic matter) or as sclerotia in the soil (for more than 3 years). Disease development is favored by warm temperatures, dry (or very well drained) soils and stressed plants. Symptoms of Rhizoctonia root rot may begin as stunted plant growth (with poor root systems) with the appearance of brown lesions at the base of the stem causing wilting with lesions eventually girdling the stem and killing the infected plant. Rhizoctonia root rot infections only extend about an inch above the soil surface (Figure 1), unlike Phytophthora blight infection which can extend much farther up the stem. [Read more…]

Filed Under: Vegetable Crops Tagged With: , , ,
July 27, 2023

Controlling Phytophthora blight in eggplant

Phytophthora blight, caused by Phytophthora capsici, can cause crown and fruit rot in eggplant. Unfortunately, most of New Jersey has been plagued by heavy rains and pop-up thunderstorms these past few weeks making conditions ideal for pathogens such as Phytophthora blight on pepper, eggplant, tomato, and cucurbit crops.

Control of Phytophthora blight is extremely difficult (even with the use of fungicides) in the very hot, wet weather conditions that most of New Jersey has been through during the month of July. In the past few years a number of new fungicides, with new active ingredients, have become commercially-available for use on multiple crops. Mefenoxam and metalaxyl, both once widely-used to effectively control Phytophthora blight have been hit by resistance issues around much of Southern New Jersey. Growers with a known history of mefenoxam-insensitivity on their farm should use Presidio or Ranman plus a Phosphite fungicide in rotation in their drip application programs for the control of the crown rot phase of Phytophthora blight. Importantly, if mefenoxam has not been used in particular fields on any crop for a number of years (more than 5+) the fungus may revert back to being mefenoxam-sensitive and control with these products may return. Mefenoxam, metalaxyl, and the phosphite fungicides are the most systemic of the group and should readily be taken up the by plant via application through the drip. Orondis Gold (OXTP + mefenoxam) is also systemic. Presidio is locally systemic, and Ranman has protectant activity and can also be applied via drip.
[Read more…]

Filed Under: Vegetable Crops Tagged With: ,
July 27, 2023

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 2022/2023 Mid-Atlantic Commercial Vegetable Production Recommendations Guide.

Phomopsis fruit rot in eggplant

Filed Under: Vegetable Crops Tagged With: , ,
July 26, 2023

Vegetable IPM Update 7/26/23

Sweet Corn

Fall armyworm (FAW) is increasing in coastal areas, and has been detected at several interior sites as far north as Ocean County. Some infestations in whorl corn are in excess of 20%.  It is very possible that economic infestations are present in much of southern New Jersey now.  Growers are advised to check whorl and seedling stage corn plantings weekly for signs of FAW.  Consider treating if infestation rates exceed 10%.  This pest is capable of significant injury to sweet corn plants, resulting in severe stunting and failure to produce viable ears.

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