Andy Wyenandt

Purple spot, caused the soil-borne fungus, Stemphylium vesicarium, can cause problems in cool, wet springs as well. 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.

Twelve hours of wetness is needed for infection and the disease is exacerbated by wind-blown sand injury. Heavy purple spot infection during the summer will lead to premature defoliation which will decrease carbohydrate reserves for the next production season. With the season we had last year and the wet spring we’ve had thus far this year season, pressure due to purple spot may be high. Control of purple spot can be difficult because of management issues (i.e., the mowing and chopping up and leaving of old fern material in the field) and because fungicides can’t be applied during the harvest season. Growers who had pre-mature defoliation issues last year may expect problems this spring. Controlling purple spot begins with preventative fungicide applications during summer and fall by reducing infections to ferns and stalks. Weekly scouting and timely fungicide applications once fern stalks are full size should be done. Apply and rotate azoxystrobin at 6.2 to 15.5 fl oz 2.08F/A or chlorothalonil at 2.0 to 4.0 pt/A.

The new 2015 Commercial Vegetable Production Recommendations guide is now available.

Every year horticulturists, plant pathologists, entomologists and weed specialists from Penn State University, Rutgers, University of Delaware, Virginia Tech, University of Maryland and West Virginia University meet to discuss what changes should be made to the guide based on new research results and changes in the vegetable industry.     ~Elsa Sanchez, PSU

At NJAES, we are proud collaborators in the pursuit of evidence-based, environmentally-sound agricultural practices. We sometimes refer to the Recommendations as the $50-million growers guide because of the cumulative effort, scientific wisdom, and practical experience found within its pages; make no mistake, its a stunning return on investment for anyone who grows or eats vegetables in the mid-Atlantic states (Rabin did the math).

The guide is available online @ Rutgers NJAES | Commercial Vegetable Production Recommendations

For a hardcopy of the guide:

• Attend the NJ Ag Convention and Trade Show
  held Feb 3-6, 2015 @ The Tropicana Casino and Resort, Atlantic City, NJ;
• Or, contact your local Rutgers Cooperative Extension Office.

Seed treatment and selected fungicides and bactericides labeled for greenhouse use tables can be found in the 2015 Commercial Vegetable Production Recommendations guide.

All seed used in transplant production, as well as any transplants brought into the greenhouse should be certified ‘clean’ or disease-free. Important diseases such as Bacterial leaf spot of tomato and pepper can cause major problems in transplant production if introduced in the greenhouse. Bacterial leaf spot of tomato and pepper can be seed-borne and infested seed can be a major source of inoculum in the greenhouse and cause problems in the field later in the growing season.

As a rule for any crop, any non-certified or untreated seed should be treated, if applicable, with a Clorox treatment, or hot-water seed treatment, or dusted to help minimize bacterial or damping-off diseases.

For more information on seed treatments for specific crops please see Table E-14 on page E45 in Section E of the 2015 New Jersey Commercial Vegetable Production Recommendations Guide.
An updated table for selected fungicides and bactericides labeled for greenhouse use is available in Section E of the 2015 recommendations guide. The table includes a comprehensive list of fungicides and biological agents approved for greenhouse use. Table E-15 can be found on pages E46-48.