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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Veg IPM Update: Week Ending 7/15/15

Sweet Corn

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There is still very little European corn borer (ECB) adult activity at this time. Few individuals have been captured throughout NJ this past week (see ECB map). ECB infestations are absent from sweet corn plantings. We would expect to see signs of the second flight within the next week or so.

As always, consider treating when the number of infested plants in a 50 plant sample exceeds 12%. Any planting remaining at or above threshold as it proceeds to full tassel should be treated, as this is the last stage at which ECB larvae will be exposed and vulnerable to insecticidal sprays.

See the 2015 Commercial Vegetable Recommendations Guide for insecticide choices.
[Read more…]

Intro to Organic Vegetable Production Field Day from Penn State, Aug 6, 2015

Location
Good Work Farm
4791 Rock Road
Zionsville, PA 18092

Date: August 6, 2015 from 4 to 7 pm
4:00 PM Farm Tour
4:45 PM Scouting and Identification Exercise
5:45 PM Disease Management and Discussion
6:30 PM Dinner

Registration
This field day is part of the Introduction to Organic Vegetable Production series. No pre-registration is required. Walk-in to join us. $10 walk-in fee covers dinner and materials.

Penn State Extension is offering An Introduction to Organic Vegetable Production Field Day focusing on plant disease scouting, identification, and management on the evening of August 6th at Good Work Farm in Zionsville, PA located about an hour north of Philadelphia. For more information see Organic Vegetable Production Field Day.

Of Note from UDel: Late blight Look-a-like in Potato & Late blight Lineages

Two important topics were addressed by Dr. Nathan Kleczewski, Extension Specialist in Plant Pathology at the University of Delaware this week in the Weekly Crop Update.

We have on occasion detected Phytophthora nicotiana on potato in southern New Jersey when wet weather conditions have been prolonged. The good news is that P. nicotiana, although it looks like Late blight, does not show anywhere near the destructiveness that comes with Late blight.

Last week Late blight, Phytophthora infestans, (US23) was found in tomato in Northern New Jersey. US23 has been the predominant genotype found throughout the region during the past few years. Why is knowing the genotype so important? US23 will infect both tomato and potato and has been shown be sensitive or to have intermediate-sensitivity to mefenoxam (i.e., Ridomil Gold). Knowing that US23 is present in New Jersey should put all tomato and potato growers on high alert and everyone should be scouting on a regular basis. All tomato and potato growers should initiate standard protectant fungicide programs if they already haven’t done so.

Verticillium Wilt in Eggplant

Verticillium wilt 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.

Diagnostic symptoms of Verticillium wilt in eggplant.

Diagnostic symptoms of Verticillium wilt in eggplant
Photo by Kris Holmstrom

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Leaf Mold in Tomato

Leaf mold (formerly Fulvia fulva) has been confirmed in field-grown tomatoes in Cape May County.

Leaf mold occasionally appears in high tunnel or greenhouse tomato production in New Jersey. However, under ideal conditions the disease will develop in field-grown crops. The fungus will cause infection under prolonged periods leaf wetness and when relative humidity remains above 85%. If relative humidity is below 85% the disease will not occur. The pathogen can survive (overwinter) as a saprophyte on crop debris or as sclerotia in the soil. Conidia (spores) of the fungus can also survive up to one year in the soil.

Symptoms of leaf mold on infected tomato plant. Note the bright yellow leaves and the olive-green spores developing on the undersides of leaves.

Symptoms of leaf mold on infected tomato plant. Note bright yellow leaves and olive-green spores developing on undersides of leaves.

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Veg IPM Update: Week Ending 7/8/15

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Sweet Corn

We are still between European corn borer (ECB) adult generations at this time. Very few individuals have been captured throughout NJ this past week (see ECB map). ECB infestations are almost gone from all sweet corn plantings. We would expect to see signs of the second flight within the next two weeks.

As always, consider treating when the number of infested plants in a 50 plant sample exceeds 12%. Any planting remaining at or above threshold as it proceeds to full tassel should be treated, as this is the last stage at which ECB larvae will be exposed and vulnerable to insecticidal sprays.

See the 2015 Commercial Vegetable Recommendations Guide for insecticide choices.
[Read more…]