Like clockwork, purple spot has appeared in some asparagus plantings during mid- to late-April for the past 3 years. Purple spot, caused the soil-borne fungus, Stemphylium vesicarium, can cause problems during cool, wet spring weather (much like we have had over the past week or so). Symptoms, just like its name, include numerous, sunken oval-shaped spots on spears during the harvest season and more importantly on ferns and stalks during the summer months as long as conditions are ideal for its development. Often, purple spot will disappear as quickly as in appears on spears during the spring production season depending on the local weather conditions. As soon as the weather becomes dry and warm (as it appears for the weekend), expect purple spot to disappear. [Read more…]
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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Controlling Strawberry Fruit Rots – 2017
Anthracnose Fruit Rot of Strawberry
Fruit rots in strawberry can cause significant losses if not recognized early and controlled. The use of good cultural practices such as keeping fields weed-free and promoting good drainage, long crop rotations, and preventative fungicide applications are critical.
Pathogens such as anthracnose, gray mold (Botrytis), and leather rot (Phytophthora) can become systemic problems in strawberry plantings once established. All three fungal diseases are soil-borne and once in fields can be difficult to manage over the lifetime of the planting.
The use of mulch (matted rows) to prevent/reduce soil splashing and keeping fruit from coming into direct contact with the soil surface can be beneficial in organic production systems where conventional fungicides cannot be used. Use of long crop rotations and staying away from areas of the farm with known instances of any of these pathogens is also important. Remember that same species of Colletotrichum that causes fruit rot in pepper and other crops can also infect strawberry.
UMaine to Hold International Potato Disease Summit Nov. 9, 2017
Orono, Maine — Two bacteria threatening the potato industry worldwide will be the focus of a Potato Disease Summit Nov. 9 in Bangor, Maine, convened by the University of Maine.
Plant pathologists, researchers and scientists from The Netherlands, Scotland and five U.S. states will present the latest information on the bacteria — Dickeya and Pectobacterium — that cause blackleg disease, an emerging potato seed problem.
In the past three growing seasons, Dickeya, a bacterial pathogen of potatoes, has caused significant economic losses in seed nonemergence and crop loss nationwide. In addition, an associated pathogen, Pectobacterium, has caused potato crop losses in the field and in storage. The bacteria have caused losses to the potato industry in Europe for an even longer period.
“The University of Maine is responding to this situation by holding an international summit focused on the latest research and what steps are needed to help the potato industry,” says University of Maine President Susan J. Hunter. “As Maine’s only public research university, we are a longstanding partner with the state’s potato industry in addressing its needs, including the growing threat posed by Dickeya and Pectobacterium.”
The Potato Disease Summit, 8 a.m.–5 p.m., Nov. 9 at the Cross Insurance Center, 515 Main St., Bangor, Maine, is designed for scientists, consultants, regulatory officials, and potato seed growers and buyers. It will focus on such topics as current advances in detection and diagnosis of Dickeya; an overview of Pectobacterium in the U.S.; and management of Enterobacteriaceae spread and risk.
The $80 per person fee includes materials, lunch and breaks. Registration deadline is Oct. 2 and is available online: extension.umaine.edu/agriculture/programs/dickeya-and-pectobacterium-summit.
For more information or to request a disability accommodation, contact Steve Johnson, 207.554.4373, stevenj@maine.edu.
Allium Leafminer Alert III in New Jersey
As of Friday, April 21, we confirmed that ALM is in south Jersey and it is likely that it can be found throughout the state. Infested field chives were found in East Vineland as well as in backyard chives in Atlantic County and onion sets in the Middlesex/Monmouth County area. Feeding scars have been found in wild garlic which is abundant in New Jersey. So far, adult flies have only been trapped in chives. Given how chives are harvested, it is difficult to assess how damaging the fly will be to the chive crop. More of a problem will be protecting longer term crops like leeks and onions. [Read more…]
Update on Use of Chateau for Weed Control in Potato
Chateau herbicide has a supplemental label for application to potatoes after hilling for preemergence suppression of various broadleaf weed species. This supplemental label will expire on June 30, 2017 and Chateau must not be used on potato after this date.
This supplemental label will not be renewed by Valent as the company is in the process of putting this supplemental label on the federal label. However, this use for potatoes will show up on the revised federal label when it reissues from the EPA.
We currently do not have a time frame for that but it probably will not before June 30. We are expecting that the revised federal label will be issued prior to the use season next year.
Allium Leafminer Alert II in New Jersey
A survey of fields from Princeton/Pennington in Mercer County northward through Milford and Asbury (Hunterdon County) and east to Chester in central Morris Co. revealed heavy allium leafminer feeding and active adults in chives only. There was only one garlic plant at the Pennington site that had feeding signs. Yellow sticky cards from chive plots in the Princeton area had numerous adults, but cards from a garlic field in Pennington did not have leafminers despite being within 200 yards of an infested chive plot.
At this point, allium leafminer adults appear to be favoring chives for feeding and egg laying. As one of the earliest and most succulent allium leaf types, chives may be a good indicator of the onset of adult activity, and could be useful as we decide when to begin protecting our other allium crops, including overwintered leeks, garlic and onion plants now being transplanted. Because egg laying is now happening, the prudent course of action would be to protect these crops, either with row covers or with recommended insecticides. These include Trigard, Scorpion, Radiant and Entrust (OMRI-approved). For a complete list see the RCE Vegetable Crops Online Resource Center Critical Updates to the Mid-Atlantic Commercial Vegetable Recommendations.
If you wish to inspect crops in your area, start with chives. Observe the tallest leaves first, and look for lines of characteristic white spots. These are wounds made by the female as she pierces the leaves to lay eggs and extract plant sap on which to feed (see photo below).
Allium leaf miner oviposition scars on garlic.
As a review, allium leafminer has spread from Pennsylvania into New Jersey, New York, and Maryland. At present, the main area of infestation in New Jersey appears to be in the northern counties. Only one suspected fly has been caught (Fall, 2016) in southern New Jersey in East Vineland. Traps set in this southern area will be checked this week. The Vegetable IPM Program will continue to track the spread and population levels of ALM in New Jersey.
