Cranberry Root Rot (CRR) is a disease in

cranberries Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus ''Oxycoccus'' of the genus ''Vaccinium''. In Britain, cranberry may refer to the native species ''Vaccinium oxycoccos'', while in North America, cranberry m ...

that can cause a decline in yield.

Hosts and symptoms

It is categorized by a decline in vine density, and more severe cases can result in dieback of vines over larger areas. A reduction in root mass can also cause secondary symptoms associated with nutrient deficiency. Symptoms can also mirror drought stress, such as chlorosis and wilting. The disease infects the root tissue, limiting its ability to take up water and nutrients, causing these secondary symptoms.

Disease cycle

CRR is usually caused by ''

Phytophthora cinnamomi ''Phytophthora cinnamomi'' is a soil-borne water mould that produces an infection which causes a condition in plants variously called "root rot", "dieback", or (in certain '' Castanea'' species), "ink disease". The plant pathogen is one of the wo ...

,'' but other ''Phytophthora'' pathogens may be responsible as well. ''Phytophthora'' pathogens are a

oomycete Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the resul ...

s, which indicates that water plays an important role in their lifecycle. The root tissue is infected by the

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or mo ...

s, the motile life stage of the pathogen, which possess two flagella. The pathogen will eventually produce sporangia, if conditions are favorable, which will produce additional zoospores. Under unfavorable conditions, the pathogen will produce asexual chlamydospores which are more resistant to desiccation and cold conditions than the mycelium of the pathogen. Once the conditions become favorable once more, the chlamydospore will produce a sporangium. The sporangia will release zoospores, continuing the lifecycle of the pathogen

Management

The most important aspect of CRR management is proper drainage. Proper drainage will decrease survivability of the pathogen enough that it will not likely progress to disease. The spread of the pathogen relies on the mobility of the zoospores, which swim using flagella, so limiting soil moisture decreases the ability of zoospores to swim through the soil water. Presence of the inoculum alone is generally not enough to induce disease symptoms, as ''Phytophthora'' inoculum is commonly present in irrigation water. Environmental controls, like transitioning from drip irrigation to sprinklers and care to not overwater has been shown to help in other ''

Vaccinium ''Vaccinium'' is a common and widespread genus of shrubs or dwarf shrubs in the heath family (Ericaceae). The fruits of many species are eaten by humans and some are of commercial importance, including the cranberry, blueberry, bilberry (whort ...

'' species

References

{{reflist Plant diseases Phytophthora