Pythium Myriotylum Research Articles

Pod Breakdown Resistance in Peanuts1

Abstract During 19 69–73, 13 commonly grown Virginia-type peanut (Arachis hypogaea L.) cultivars, 15 plant introductions. and two breeding lines were evaluated under field conditions for resistance to the pod breakdown fungi Pythium myriotylum and Rhizoctonia solani. Four cultivars—Early Runner. Florunner, Florigiant, and NC 17—having related pedigrees were consistently more resistant to infection by these two fungi. P.I. 341880 and P.I. 341885 and Florida breeding line F439–16–6 showed similar resistance to infection. Cultivars most susceptible to pod breakdown were NC 5, Va. 56R, Ga. 119–20 and Va. 72R. P.I. 343410 and a selection from P.I. 319178 were extremely susceptible to pod breakdown. Resistance to pod breakdown seems to have been derived from a cross between a small, white-seeded Spanish-type peanut and Dixie Giant, a large-seeded Virginia-type peanut. All resistant cultivars are related to this cross, whereas the susceptible cultivars lack these parental types in the pedigrees.

Interactions of Pythium myriotylum with Several Fungi in Peanut Pod Rot

Interactions of Pythium myriotylum with Several Fungi in Peanut Pod Rot

Synergistic Interactions of Pythium myriotylum with Fusarium solani and Meloidogyne arenaria in Pod Rot of Peanut

Synergistic Interactions of Pythium myriotylum with Fusarium solani and Meloidogyne arenaria in Pod Rot of Peanut

Effect of Constant Moisture Levels on Pythium Rot of Peanut Pods

Different constant levels of topsoil moisture were established by upward capillary movement of water from a basin through soil columns of different heights and were used to determine the influence of soil moisture on development of rot of peanut pods by Pythium myriotylum. Roots obtained water from a wet subsoil, whereas pods developed in a Pythium-infested, sandy, well-aerated topsoil. The wetter the topsoil, the higher the incidence of infected pods. However, some pod rot developed even in soil drier than the wilting range for mesophytes.

The Influence of Calcium on the Susceptibility of Peanut Pods to Pythium Myriotylum and Rhizoctonia Solani1

Abstract No correlation was found between calcium applied at an equivalent rate of either 897 or 1,793 kg/ha in an artificial medium and the amount of pod breakdown incited by either Pythium myriotylum or Rhizoctonia solani. R. solani appeared to be the dominant organism although the isolates tested exhibited a wide range of pathogenicity to peanut pods.

Phytophthora drechsleri Tucker and Pythium spp. as pathogens of safflower in New South Wales

Pythiaceous fungi associated with a widespread root rot disease of safflower (Carthamus tinctorius) in New South Wales include Phytophthora drechsleri, Pythium myriotylum, Pythium ultimum Pythium irregulare, Pythium acanthicum, and a number of sterile Pythium spp. Pathogenicity of these fungi was tested against safflower seedlings and older plants growing either in soil with moisture content at field capacity or in flooded soil. Phytophthora drechsleri, Pythium myriotylum, Pythium ultimum and Pythiumirregulare caused severe pre-emergence damping off. When safflower plants, three and eight weeks old, were inoculated with each of the fungi, only Phytophthora drechsleriand Pythium myriotylum killed a high proportion of plants. The pathogenicity of Phytophthora drechsleri, Pythium myriotylum, Pythium ultimum, and Pythium irregulare was increased by flooding the soil for ninety hours after inoculation. Phytophthora drechsleri was isolated from naturally infected saffron thistle (Carthamus lanatus). Cross inoculation tests with Phytophthora drechsleri isolates from safflower and saffron thistle showed that both isolates could infect each host. Saffron thistle could be an important alternative host of Phytophthora drechsleri in the field. It is concluded that Phytophthora drechsleri is the major cause of root rot of safflower in New South Wales.

Effect of Gypsum and Dolomite on Pythium Diseases of Seedlings1

Abstract The addition of gypsum (10, 5 or 2½ lb./yd3) or gypsum plus dolomite (each 5 lb./yd3) to soils before planting with 7 kinds of ornamental and vegetable seeds did not result in more useful seedlings in uninfested soil, but in most instances, significantly increased percent of good seedlings in soil infested with Pythium myriotylum or P. aphanidermatum over the control. In uninfested soils the addition of 5 lb./yd3 dolomite did not increase the number of useable seedlings compared with unamended, uninfested soil. The dolomite resulted in significantly more useful, healthy seedlings than the control only with tomato and calendula in P. myriotylum-infested soil and in stock with P. aphanidermatum-infested soil.

Pythium myriotylum and Fusarium solani as Cofactors in a Pod-Rot Complex of Peanut

Pythium myriotylum and Fusarium solani as Cofactors in a Pod-Rot Complex of Peanut

Effect of Soil Temperature on Virulence of Pythium aphanidermatum and Pythium myriotylum to Rye and Tomato

Effect of Soil Temperature on Virulence of Pythium aphanidermatum and Pythium myriotylum to Rye and Tomato

Premature Death of Groundnut Plants in Northern Nigeria

SummaryPremature wilting and death of groundnut plants in Northern Nigeria was caused mainly by termites excavating the xylem tissue of the root. Lepidopterous larvae which damaged the crown of the plant were a less common cause. Occasional wilted plants had discoloured vascular systems from which Pythium myriotylum was consistently isolated. Wilting was also caused by mechanical damage inflicted during weeding operations. Complete severance or blockage of the water-conducting tissue of the primary root did not result in immediate death of plants, because the pods and pegs were able to absorb sufficient moisture to maintain the leaves above permanent wilting point until the onset of the dry season.

Hyphal cell wall structure of two species of Pythium.

Hyphal cell walls were prepared by ultrasonication. Glucose was the only sugar detected in both species. Evidence was obtained indicating that the Pythium butleri Subram. glucan is beta 1,2-linked, and that the glucan of Pythium myriotylum Drechsler is beta 1,4-linked. Sixteen amino acids were detected in P. butleri cell wall hydrolysates. Four of these amino acids were absent from P. myriotylum preparations. Similar quantities of lipid were found in both species. The significance of these data for fungal classification is discussed.