Pythium root rot has been observed in several growing systems this spring . Pythium species incline to have broad host ranges and all greenhouse crops are susceptible to transmission under the right circumstances . It is particularly troublesome in overwatered or poorly drain get media , and in aquacultural systems .
symptom of Pythium radical rot include stunting , wilting , yellowed leave , plant prostration , and death . It is always advisable to inspect the beginning scheme of plants with these symptoms . septic root will be browned and delicate , sometimes with a “ rat - tail ” appearing as the KO’d pallium of the root slough off , leaving the vascular piston chamber behind . Some specie cause severe disease with a rapid onset , while others cause a chronic contagion that progresses more slow . Disease severity is also subordinate on temperature , as the optimum range for growth and transmission varies among coinage .
Pythium is not a “ straight fungus . “ It is an Oomycete or “ water mould , ” a group of organisms more closely related to algae . Most Pythium species spread by means of zoospores , nomadic spores which have flagella ( transportable tails ) that provide them to float through soil wet . The zoospores are drawn to potential host plant by substances naturally produced by growing root . The zoospore swim to the base and form a cyst on the control surface before proceeding to infect server tissue . It is sluttish to envisage how such an organism can thrive in moist soil or hydroponic organization .
Many Pythium specie also form oospores , reproductive structures that may be get a line in infected roots and are an important diagnostic feature article under the microscope . These oospores have thick walls and are project to resist untoward environmental conditions such as desiccation . In this way , Pythium can subsist in contaminated soil and in aquicultural systems for a long prison term .
Sanitation is vital for successful Pythium management . Do not reprocess potting media . head off re - using pots if possible ; if crapper are to be re - used , they must be soundly scavenge and all organic affair removed before treating with a antimicrobic such as 4th ammonium ion or 10 % blanching agent . Similarly , all organic matter and biofilms must be removed from hydroponic systems prior to disinfection . Pythium also thrives when nitrogen is abundant , so excess fertilization should be annul .
Because they are not rightful fungus , Pythium is not involve by most of the ceremonious fungicides used for pathogens such as Botrytis and Alternaria . Maneb and azoxystrobin are two exclusion to this normal . Most product usable for Pythium prevention and management are specific either to the Oomycetes or to Pythium itself . Organic ware have no therapeutic qualities and must be utilize in a preventative style . Several conventional and organic products are labeled for Pythium direction : for a full list , please see the New England Greenhouse Management Guide .
For more information : University of Massahussets Amherstwww.umass.edu
