Fruit and Vegetable Weekly Crop Update

Aug 25, 2015

Growing degree days since April 1: 2788 GDD (Average (11 year): 2572) (From the Illinois State Water Survey Degree-Day Calculator)

4 inch soil temp: 74.8°F (10 am 4-inch soil temperature under bare soil) (From the Illinois State Water Survey Illinois Climate Network)

Downy mildew of basil in Illinois. On August 10, R. Mohammad Babadoost observed and confirmed downy mildew of basil in the University of Illinois research plots in Champaign. He expects downy mildew on basil develop throughout the state. Thus, fungicide treatment for control of the disease on green basils is essential. Downy mildew of basil, caused by Peronospora belbahrii, occurred first in Illinois in 2009. Since then the disease developed on basils every year. P. belbahrii infects leaves, rapidly develops and spreads, and can cause total crop loss. Since 2009, we have had trials for evaluating efficacy of fungicides for control of basil downy mildew every year. The results of our trials showed that the disease can be effectively controlled by weekly applications of the following fungicides: Quadris, Revus, and Ranman. These fungicides have different modes of action and all three are registered for downy mildew of basils. To prevent resistance development of in the pathogen, the fungicides should be alternated – follow the label guidelines. For additional information, contact Mohammad Babadoost by email (babadoos@illinois.edu) of phone 217-333-1523.

For organic growers, Cornell University, Vegetable MD Online recommends the following: Actinovate AG (active ingredient is Streptomyces lydicus), Double Nickel 55 (Bacillus amyloliquefaciens), MilStop (potassium bicarbonate), Regalia (extract of Reynoutria sachalinensis), Trilogy (neem oil), and OxiDate (hydrogen dioxide) are OMRI-listed fungicides labeled for use on herbs and for suppressing foliar diseases including downy mildew. MilStop, Regalia, and OxiDate are labeled for use outdoors and in greenhouses. The Actinovate, Double Nickel and Trilogy labels do not have a statement prohibiting use in greenhouses. Double Nickel label has directions for greenhouse use for soil-borne pathogens. OxiDate has limited residual activity and thus if used should be combined with or followed by another product. Results from research conducted at Cornell are available on-line.

Spotted wing Drosophila (SWD) numbers continue to increase in traps and fruit samples from the University of Illinois Fruit Research Farm at Urbana. For everyone with blackberries, red raspberries, and late peaches that you wait to harvest until they are really ripe … infestations will continue to increase. See the March 19, 2015, issue of the Illinois Fruit and Vegetable News for details on sampling and control (Dr. Rick Weinzierl, University of Illinois).

Source: University of Illinois Board

Video: LALEXPERT: Sclerotinia cycle and prophylactic methods

White rot, also known as sclerotinia, is a common agricultural fungal disease caused by various virulent species of Sclerotinia. It initially affects the root system (mycelium) before spreading to the aerial parts through the dissemination of spores.

Sclerotinia is undoubtedly a disease of major economic importance, and very damaging in the event of a heavy attack.

All these attacks come from the primary inoculum stored in the soil: sclerotia. These forms of resistance can survive in the soil for over 10 years, maintaining constant contamination of susceptible host crops, causing symptoms on the crop and replenishing the soil inoculum with new sclerotia.