Sclerotinia White Mould – An Occasional Pest of Ginseng

Sclerotinia white mould, which is caused by the fungus Sclerotinia sclerotiorum and other species of Sclerotinia, is a major disease of a wide variety of crops including legumes, carrots, lettuce, sunflower and cole crops. It is often easily recognizable due to its cottony white mycelium (fungal body) and hard black survival structures called sclerotia. It is usually found under very humid conditions in dense plant canopies. If you have grown beans in the garden, you have probably seen Sclerotinia attacking the stem and pods under wet conditions. 

There have only been a few reported occurrences of Sclerotinia in ginseng and the symptoms are not as easily recognizable as in other crops. It can occasionally be found attacking the lower stem near the straw and can look similar to other stem diseases such as Rhizoctonia and Alternaria (Figure 1). This pest may occasionally be found in ginseng gardens, especially under the very humid and warm conditions experienced over the past week. It may also attack broadleaf weeds in a ginseng garden and may cause damage to nearby ginseng stems. Little is known about Sclerotinia on ginseng, and the potential for minor economic damage from this disease cannot be ruled out, but has not been reported previously.

The Pest Management Regulatory Agency recently approved the registration of Serenade Max for the control of Sclerotinia white mould for the entire Root and Tuber Vegetable Crop Group which includes ginseng. Serenade Max is a biological product composed of the QST 713 strain of the bacteria Bacillus subtilis. It is registered for a wide range of crops in Canada. In other crops it is mainly registered for suppression of foliar and stem diseases including Alternaria, Botrytis, powdery mildew, downy mildew and bacteria. 

Preventative sprays of Serenade Max for control of Sclerotinia white mould are not required in most ginseng gardens. However, if you have had Sclerotinia problems in the past, Serenade Max should be applied preventatively when conditions favour disease development at a rate of 2.0-4.0 kg/ha in sufficient water to cover all above-ground plant surfaces. Apply at 7-10 intervals. Shorten the spray interval and apply the high rate when disease pressures increase. Serenade Max has a 0 day pre-harvest interval, meaning that it can be applied up to and including the day of harvest. 

Figure 1. Sclerotinia sclerotiorum was isolated from this ginseng stem. Note the damage to the lower stem.

New Crops Workshop – Last Week to Register

New Crops, Old Challenges:
Non-traditional crops integrated crop management workshop

Come out to the Simcoe Research Station to learn about:

- Non-traditional and specialty crops: demonstration plots of example crop
- Pest management and sprayer technology: discuss with provincial specialists
- Cover crops: opportunities to save your nitrogen dollars 
- Current nitrogen research conducted by the University of Guelph
- Enjoy refreshments, meet with other producers and take the opportunity talk with the University of Guelph staff and OMAFRA specialists

Date: Tuesday August 18, 2009
(Rain Date: Thursday August 20, 2009)
Time: 1:30 p.m.-5:00 p.m.
Place: Simcoe Research Station

THIS IS THE LAST WEEK TO REGISTER!
REGISTRATION IS FREE: CALL 519-426-7127 ext. 323

Questions about ginseng can be directed to Sean Westerveld, OMAFRA’s Ginseng and Medicinal Herbs Specialist at 519-426-4323; E-mail: sean.westerveld@ontario.ca.