DISINFESTATION OF RECIRCULATING NUTRIENT SOLUTION BY FILTRATION AS A MEANS TO CONTROL PYTHIUM ROOT ROT OF TOMATOES

2005 ◽  
pp. 303-308 ◽  
Author(s):  
J.C. Tu ◽  
B. Harwood
Keyword(s):  
Nutrient Solution ◽  
Root Rot ◽  
Pythium Root Rot

scholarly journals Etiology and epidemiology of Pythium root rot in hydroponic crops: current knowledge and perspectives

2006 ◽  
Vol 32 (4) ◽  
pp. 307-321 ◽  
Author(s):  
John Clifford Sutton ◽  
Coralie Rachelle Sopher ◽  
Tony Nathaniel Owen-Going ◽  
Weizhong Liu ◽  
Bernard Grodzinski ◽  
...  
Keyword(s):  
Nutrient Solution ◽  
Root Rot ◽  
Root Zone ◽  
Pythium Ultimum ◽  
Stress Factors ◽  
Pythium Root Rot ◽  
Whole Plant ◽  
Phenolic Substances ◽  
Hydroponic Systems ◽  
The Impact

The etiology and epidemiology of Pythium root rot in hydroponically-grown crops are reviewed with emphasis on knowledge and concepts considered important for managing the disease in commercial greenhouses. Pythium root rot continually threatens the productivity of numerous kinds of crops in hydroponic systems around the world including cucumber, tomato, sweet pepper, spinach, lettuce, nasturtium, arugula, rose, and chrysanthemum. Principal causal agents include Pythium aphanidermatum, Pythium dissotocum, members of Pythium group F, and Pythium ultimum var. ultimum. Perspectives are given of sources of initial inoculum of Pythium spp. in hydroponic systems, of infection and colonization of roots by the pathogens, symptom development and inoculum production in host roots, and inoculum dispersal in nutrient solutions. Recent findings that a specific elicitor produced by P. aphanidermatum may trigger necrosis (browning) of the roots and the transition from biotrophic to necrotrophic infection are considered. Effects on root rot epidemics of host factors (disease susceptibility, phenological growth stage, root exudates and phenolic substances), the root environment (rooting media, concentrations of dissolved oxygen and phenolic substances in the nutrient solution, microbial communities and temperature) and human interferences (cropping practices and control measures) are reviewed. Recent findings on predisposition of roots to Pythium attack by environmental stress factors are highlighted. The commonly minor impact on epidemics of measures to disinfest nutrient solution as it recirculates outside the crop is contrasted with the impact of treatments that suppress Pythium in the roots and root zone of the crop. New discoveries that infection of roots by P. aphanidermatum markedly slows the increase in leaf area and whole-plant carbon gain without significant effect on the efficiency of photosynthesis per unit area of leaf are noted. The platform of knowledge and understanding of the etiology and epidemiology of root rot, and its effects on the physiology of the whole plant, are discussed in relation to new research directions and development of better practices to manage the disease in hydroponic crops. Focus is on methods and technologies for tracking Pythium and root rot, and on developing, integrating, and optimizing treatments to suppress the pathogen in the root zone and progress of root rot.

Identification of metalaxyl and ethaboxam insensitive Pythium sylvaticum pathogenic to pulse crops in Montana, USA.

2021 ◽  
Author(s):  
Lipi Parikh ◽  
Swarnalatha Moparthi ◽  
Frankie Crutcher ◽  
Mary Burrows
Keyword(s):  
Root Rot ◽  
Damping Off ◽  
Management Options ◽  
Fungicide Sensitivity ◽  
Root Rots ◽  
Pulse Crops ◽  
Pythium Root Rot ◽  
Pythium Sylvaticum ◽  
Potential Pathogenicity

Pythium root rot and damping-off caused by Pythium spp. are important diseases of pulse crops. In a 2016 pathogen survey from dry pea growing fields in Montana, along with commonly known causal agents P. ultimum and P. irregulare, an isolate identified as P. sylvaticum (LPPY17) was isolated from the rhizosphere of a diseased pea plant collected from Valley County, MT. Root rots and damping-off caused by P. sylvaticum have not previously been reported for chickpea, pea, and lentil crops. The isolate LPPY17 was tested for fungicide resistance in vitro, and results indicated a reduced sensitivity to metalaxyl and ethaboxam containing fungicides. LPPY17 was also tested for pathogenicity on chickpea, pea, and lentil seedlings in the greenhouse, and the results from the study revealed LPPY17 is capable of causing both root rots and damping off. Due to the potential pathogenicity and reduced fungicide sensitivity of this species, in the future it will be important to monitor for P. sylvaticum in pulse root rot surveys and diagnostics, as management options may be different from other common Pythium spp.

STUDIES ON BROWNING ROOT ROT OF CEREALS: VI. FURTHER CONTRIBUTIONS ON THE EFFECTS OF VARIOUS SOIL AMENDMENTS ON THE INCIDENCE OF THE DISEASE IN WHEAT

1940 ◽  
Vol 18c (6) ◽  
pp. 240-257 ◽  
Author(s):  
T. C. Vanterpool
Keyword(s):  
Root Rot ◽  
Nutrient Deficiencies ◽  
Sweet Clover ◽  
Poor Growth ◽  
Prairie Soils ◽  
Pythium Root Rot ◽  
The Poor ◽  
Copper Manganese ◽  
Supplemental Nutrients ◽  
Severe Leaf

Further work has substantiated earlier findings that phosphatic fertilizers and farm manure will give adequate control of Pythium root rot of wheat in infested prairie soils. The improvement in growth resulting from these amendments is considered to be due to the production of a larger number of quicker growing roots which lessens the chances for infection and leaves more roots healthy, though the same percentage may be affected as in diseased plants showing severe leaf discolorations. Experiments have failed to indicate that the phosphatic materials increase resistance appreciably. Nitrogenous materials when applied singly had virtually no effect on growth, but once ample phosphorus was added, further nitrogen applications gave substantially greater increases than phosphate alone. Phosphorus is apparently the chief limiting element. No difference was found in preliminary tests in the phosphate-fixing power of browning and normal soils. Typical browning soils responded irregularly to small applications of boron, copper, manganese, or zinc, but were not found to be seriously lacking in these elements. Moderate benefits resulted from heavy applications of gypsum and of sulphur. Browning soil was found also to be deficient in phosphate for non-cereals such as alfalfa, buckwheat, carrots, flax, lettuce, and sweet clover. These crops were not attacked by the Pythium spp. pathogenic to cereals. Consequently the poor growth of the non-cereals in browning soil appears to be due to nutrient deficiencies, while the poor growth of cereals is due to both root-destroying fungi and nutrient deficiencies. In both instances phosphorus is probably the chief limiting element. Ground cereal straw, sweet clover hay, and weed hay amendments gave moderate increases m the growth of wheat. No consistent differences were found in the carbon-nitrogen ratios of browning and normal soils. The results as a whole suggest that two of the most practicable means of meeting the browning root-rot situation are, firstly, to supply supplemental nutrients in the form of artificial fertilizers, and secondly, to add organic residues or farm manure regularly to fields subject to the disease.

Sanitation of Float Trays for the Management of Pythium Species in Tobacco Float Systems

2020 ◽  
Vol 21 (1) ◽  
pp. 21-25
Author(s):  
Lindsey D. Thiessen ◽  
Grant H. Ellington ◽  
Justin A. Macialek ◽  
Chuck S. Johnson ◽  
David T. Reed
Keyword(s):  
Root Rot ◽  
Pythium Species ◽  
Greenhouse Production ◽  
Pythium Root Rot ◽  
Tobacco Seedlings ◽  
Agricultural Use ◽  
Phase Out ◽  
Disease Free ◽  
Important Disease ◽  
H 30

Pythium root rot is an economically important disease threatening greenhouse production of tobacco seedlings. Although methyl bromide was historically used for tray sanitation, the phase-out of the fumigant from agricultural use has left few options for growers to produce disease-free transplants. Steam sanitation at 80°C for 30 min has shown control of disease caused by Rhizoctonia solani and has been adopted for use to manage Pythium spp. This study evaluates other steam temperatures and time durations to effectively manage Pythium spp. in float-tray systems. Naturally infested trays steamed at 63, 71, and 77°C for 30 min significantly reduced Pythium spp. from trays compared with TriSan wash and CC-15 dip treatments. Float trays inoculated with Pythium spp. that were steamed at 70 and 80°C for 2 h 30 min, respectively, also significantly reduced Pythium spp. survival. Other fungi, likely saprophytic or beneficial organisms, were not significantly impacted by any steaming treatment.

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