Monilinia oxycocci
| Monilinia oxycocci | |
|---|---|
| Scientific classification | |
| Kingdom: | Fungi |
| Phylum: | Ascomycota |
| Class: | Leotiomycetes |
| Subclass: | Leotiomycetidae |
| Order: | Helotiales |
| Family: | Sclerotiniaceae |
| Genus: | Monilinia |
| Species: | M. oxycocci |
| Binomial name | |
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Monilinia oxycocci Honey |
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Monilinia oxycocci (Woronin) Honey, (synonym Sclerotinia oxycocci), common names Cranberry Cottonball, Cranberry Hard Rot, Tip Blight, is a fungal infection of the cranberry plant (Vaccinium macrocarpon). The tips of young flowering shoots wilt before they flower. Fruit that forms on the plant can then be infected by the asexual spores traveling through the plant, causing the berries to harden, turn cottony on the inside, and dry out instead of maturing. The berries are filled with a cotton-like fungus and are generally yellowish with tan stripes or blotches at maturity, making them unmarketable. It results in important economic impacts on many cranberry marshes, particularly in Wisconsin.
Cottonball occurs on cranberry marshes in the Pacific Northwest and southeastern Canada, but is more common in Wisconsin. The disease has become much more problematic in Wisconsin since the 1970s “for reasons that are not known.” Typically 2 to 10% of fruit in diseased beds is infected; if left unchecked the amount can exceed 40%. Cottonball has been observed on all of the popular cranberry varieties in Wisconsin.
When young cranberry shoots become infected, they show “tip blight” symptoms: shoot tips shrivel and a tan discoloration spreads from the tip of the shoot down the stem and into leaves. Cottonball tip blight differs from other shoot diebacks, in that tan V- or U-shaped lesions can be observed centered on the leaf midvein. Also, white, powdery conidia (asexual spores) appear on diseased shoots just before and during bloom. Tip blight of cottonball is often inconspicuous and is easily overlooked.
Immature diseased berries show no external symptoms, but are filled with white, cotton-like fungus. While healthy berries turn red as they mature, diseased berries may acquire a red blush but are generally yellowish with tan stripes or botches. Diseased fruit are unfit for fresh or processing markets.
Dried-up remains of diseased fruit contain sclerotia and are commonly called “mummies.” The “mummies” are roughly spherical and about ½ inch in diameter. In the spring, tan or brown mushroom-like structures (apothecia) about 1-2 inches tall grow from the mummies. “'Mummies' and apothecia are difficult to spot."
Monilinia species attack various Ericaceae hosts. M. oxycocci on cranberry exhibits a disease cycle similar to other species and is characterized by two distinct phases: infection of shoots (tip blight), and secondary infection of flowers (leading to fruit rot). Fruit rot only results from the infection of flowers during bloom.
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Wikipedia