Aphanomyces cochlioides

Aphanomyces cochlioides
Scientific classification
Domain:	Eukaryota
Clade:	Diaphoretickes
Clade:	SAR
Clade:	Stramenopiles
Phylum:	Oomycota
Order:	Saprolegniales
Family:	Leptolegniaceae
Genus:	Aphanomyces
Species:	A. cochlioides
Binomial name
Aphanomyces cochlioides Drechsler, (1929)
Synonyms

Aphanomyces cochlioides is a plant pathogen that can affect commodity crops like spinach, Swiss chard, beets and related species. In spinach the pathogen is responsible for the black root "rot" that can damage plants.

Most commonly infection occurs on older roots that have already begun to grow, but if infection of a younger root occurs it can be identified by the excess growth of lateral roots- which is a common plant response to loss of the main taproot.^[1] Infection symptoms above ground will include chlorotic, non-vigorous, leaves that will not maintain turgor during the stress of hot sun, but will maintain the ability to revive during less stressful times such as cloudy days or overnight.^[2] To discern from other common beet revive during less stressful times such as cloudy days or overnight. To discern from other common beet diseases such as Rhizoctonia or Pythium root rot, leaves can be tested for brittleness or a burned or scorched appearance.^[3] It is also uncommon for a plant infected with Alternaria to become permanently wilted which is often the case in the previously mentioned pathogens. below ground root growth is often stunted as a result of lesions. The lesions have a water-soaked appearance and might be superficial. As the disease progresses down the stem and into the root the water-soaked spots will become darker as well as the interior of the root. An infected root will often have rotting around the tip leaving behind only vascular bundles, classifying it as a tip rot.^[4] If conditions for the plant are favorable it is possible for the crop to recover; however the root will still show signs of the infection such as dark spots, or scarring. There is an acute phase of the disease known as black root. This occurs April through June and will affect the younger plants. This can be especially devastating if warm, moist, conditions prevail in which seedlings can be destroyed within three to four days. The chronic phase, or root rot, occurs June through August in the latter part of the season in which the plants survived the first round of infection. This will be characterized by the wilt-recovery cycle of leaves and the root turning black from the inside out.