Modern cranberry producers utilize a diverse array of pest management and horticultural techniques to produce a marketable crop. In a typical commercial setting, three to five fungicide applications are made during the growing season and resultant field rot levels range from less than 1% to 15%. Fruit rot infected lots beyond 12% are heavily discounted and lots with >20% are not accepted by cranberry handlers (cranberry processing industry). Some growers are seeing their entire delivery of fruit rejected for rot levels exceeding the maximum allowed. Over the past decade, due to climate change, the fruit rot disease complex has become even more challenging for growers especially in plantings of high-yielding and newer cultivars, resulting in 50-100% yield losses if not managed strategically. Due to lack of knowledge of risk factors associated with fruit rot incidence or fruit rot forecast system, growers are applying 3-5 fungicides just to make sure their produce is marketable at the end of the season. Under current historic low cranberry prices, fungicides are putting cranberry growers at a huge economic disadvantage, while adding lot of chemical inputs into environment. Growers are also dealing with a new challenge of losing the most commonly used broad-spectrum (chlorothalonils and mancozebs) fungicides due to revised maximum residue limits (MRLs) by key export markets, owing to perceived negative impacts on pollinator (honey bees and bumble bees), human and environmental health. This is prompting the cranberry industry to rely on the only two classes of available fungicides from FRAC group 3 and 11 which are at high risk of posing fungicide resistance. For long-term sustainability of cranberry industry, it is critical to reduce overreliance on the effective fungicides, diversify fruit rot management tool kit with novel management tools that integrate cultural, chemical and biological control methods.
Our goal is to evaluate novel fruit rot management tools that integrate biologicals/OMRI (Organic Materials Review Institute) approved compounds with site-specific, newer classes of fungicides (which are less harmful to human, environmental and pollinator health) on fruit rot incidence and fruit quality in comparison with traditional grower fungicide standards.