Grape growers have access to a few new biological tools for disease management.
The active ingredient in Serifel is Bacillus amyloliquifaciens strain MBI 600. It is labeled for suppression of botrytis gray mold and powdery mildew. It has protectant activity by competing with pathogens to room and nutrients and, once established on the grapevine the bacterial spores germinate and produce metabolites that have fungicidal activity. It cannot be tank-mixed with Ridomil, Manzate or Polyram. It is rainfast after 3 hours, has a 4-hour REI and 0-day PHI and is EcoCert approved.
Stargus contains Bacillus amyloliquifaciens strain F727. Peptides in Stargus work to prevent disease infection. Stargus spores colonize the treated parts of the plant, forming a protective shield against disease infection. It is labeled for suppression of downy mildew and black rot. With the exception of copper (which can be applied in rotation), Stargus is an excellent tank-mix partner with other fungicides. While it has organic certification in the U.S., it currently does not in Canada. The company is currently pursuing this certification.
The LifeGard label expansion has finally been approved on grape for control of downy mildew and suppression of powdery mildew. Although it’s not on the Canadian label, research in Michigan also shows good activity against black rot and Phomopsis cane and leaf spot. The active ingredient in LifeGard is a naturally occurring bacterium (Bacillus mycoides isolate J) shown to trigger a plant’s natural immune response to pathogenic fungi, bacteria and viruses in the phenomenon known as ISR. Plants respond to initial detection of potentially pathogenic microorganisms by “switching on” resistance genes, causing a cascade of metabolic responses to limit infection and disease development. Within minutes the plant knows it’s there and within 3 hours starts its defense reactions. Within 24 hours it produces enzymes that attack fungi and bacteria. The product is a resistance activator with no direct antagonistic effect on plant pathogens. Note – this mode of action is protective only – it will not affect infections that have already occurred. The label recommends applications at 7-21 day intervals as part of a rotational program with fungicides.
While the label recommendations are to start considerably earlier in the growing season than where we are now (cluster close), if LifeGard is applied after a product with post-infection activity, the resistance response will kick in, so that LifeGard can be effectively rotated or tank mixed with other products.
The product has a 0-day REI and PHI. LifeGard is EcoCert approved.
While these products are organically certified (or are in the process), they are also useful rotational products for non-organic growers, especially in light of the restrictions on use of captan, the loss of Polyram in 2021 and unknown restrictions on mancozeb products in 2021.