Behaviour of Phytophthora cinnamomi in soils suppressive and conducive to root rot

1974 ◽  
Vol 25 (1) ◽  
pp. 121 ◽  
Author(s):  
P Broadbent ◽  
KF Baker
Keyword(s):  
Organic Matter ◽  
Forest Soil ◽  
Root Rot ◽  
Rain Forest ◽  
Phytophthora Cinnamomi ◽  
Nutrient Level ◽  
Soil Leachate ◽  
Suppressive Soil ◽  
Isolation Frequency ◽  
Calcium And Magnesium

Suppression of root rot in avocados caused by Phytophthora cinnamomi was demonstrated in soil from a grove at Tamborine Mt., Queensland. The addition of P. cinnamomi inoculum in amounts sufficient to cause severe root rot of plants in other soils, untreated or steam-air treated at 60°C for 30 min, produced little or no damage in the suppressive soil. Suppressive soil was found to have higher populations of bacteria and actinomycetes than soils conducive to root rot. Few sporangia were formed by P. cinnamomi and P. citrophthora in suppressive soil or soil leachate. The suppression of sporangium formation was found to be microbial and not related to the nutrient level of the soil leachate. Mycelium of P. cinnamomi grew through untreated conducive soils, but developed poorly in untreated suppressive soils. The fungus grew readily through all soils steam-air treated at 49, 60 and 100�C for 30 min. After 6 weeks the isolation frequency of P. cinnamomi had declined in the suppressive soil treated at 49 or 60°C for 30 min. Exchangeable calcium and magnesium, nitrogen, and organic matter were higher in soils suppressive to root rot than in conducive soils. Rain-forest soil, where the pathogen is not damaging, was comparable in this respect to the suppressive soil.

The Impact of Cashew (Anacardium Occidentale) on Forest Soil

1994 ◽  
Vol 30 (3) ◽  
pp. 337-341 ◽  
Author(s):  
A. O. Aweto ◽  
M. A. Ishola
Keyword(s):  
Organic Matter ◽  
Forest Soil ◽  
Rain Forest ◽  
Nutrient Status ◽  
Available Phosphorus ◽  
Nutrient Cycles ◽  
Logged Forest ◽  
Calcium And Magnesium ◽  
The Impact ◽  
Properties Of Soil

SUMMARYThe impact of a 20-year-old cashew plantation on a forest soil was evaluated by comparing the properties of soil under cashew with that under an adjoining logged rain forest. The levels of organic carbon, nitrogen, exchangeable calcium and magnesium, and available phosphorus were similar under logged forest and cashew, suggesting that organic matter and nutrient cycles in a cashew plantation are similar to those in a logged rain forest and that cashew has no significant adverse effect on soil organic matter and nutrient status.

A Forest Soil Suppressive to Phytophthora cinnamomi and Conducive to Phytophthora cryptogea. I. Survival, Germination and Infectivity of Mycelium and Chlamydospores.

1982 ◽  
Vol 30 (1) ◽  
pp. 11 ◽  
Author(s):  
DM Halsall
Keyword(s):  
Forest Soil ◽  
Recovery Rate ◽  
Phytophthora Cinnamomi ◽  
Field Trials ◽  
Chemical Characteristics ◽  
Subsequent Recovery ◽  
Suppressive Soil ◽  
Phytophthora Cryptogea ◽  
Physical And Chemical ◽  
Conducive Soil

The physical and chemical characteristics of a forest soil suppressive to P. cinnamomi are compared with those of other, previously described, suppressive soils. Recovery of P. cinnamomi chlamydospores from the suppressive soil was reduced to 51% of recovery from condilcive soil when the chlamydospores were mixed through the soil immediately prior to sampling. The subsequent recovery rate decreased more rapidly in the suppressive soil than in the conducive soil. Germination of chlamydospores by the formation of a terminal sporangium and zoospores was inhibited in the suppressive soil. Degeneration of mycelium was more rapid in the suppressive than in the conducive soil. Glasshouse tests showed infection of seedlings growing in the suppressive soil could occur when a zoospore inoculum was used. Infection was greatly reduced when a chlamydospore inoculum was used. Field trials in Tallaganda State Forest, N.S.W., indicated that P. cinnamomi introduced into this habitat rarely caused infection and was unlikely to spread.

scholarly journals Control of Phytophthora cinnamomi in Erica sessiliflora and Erica davisii

2008 ◽  
Vol 61 ◽  
pp. 86-90
Author(s):  
S.G. Casonato ◽  
M.A. Manning ◽  
P.A. Rheinlander ◽  
R.A. Fullerton
Keyword(s):  
Organic Matter ◽  
Root Rot ◽  
Field Trial ◽  
Untreated Control ◽  
Soil Amendment ◽  
Phytophthora Cinnamomi ◽  
Phosphorous Acid ◽  
Organic Soil ◽  
Health Index ◽  
The Mean

A field trial was conducted to test the efficacy of two fungicides (metalaxyl and phosphorous acid) and supplementary organic matter for the control of Phytophthora cinnamomi root rot in Erica sessiliflora and E davisii Five treatments were applied (1) untreated control (2) metalaxyl (3) phosphorous acid (4) metalaxyl plus phosphorous acid and (5) organic soil amendment Plants were assessed for plant health as an indication of possible P cinnamomi infection Phosphorous acid applied alone or in combination with metalaxyl resulted in a significant reduction in the number of diseased or dead E sessiliflora plants compared with the untreated control plants (P0011 and P0004 respectively) The mean health index of phosphorous acid treated E davisii plants was not different (P>005) to control plants Results suggest that this species of Erica has some tolerance to P cinnamomi Metalaxyl applications alone or organic matter treatments did not reduce disease relative to controls in either species

scholarly journals Cellulase Activity as a Mechanism for Suppression of Phytophthora Root Rot in Mulches

2011 ◽  
Vol 101 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Brantlee Spakes Richter ◽  
Kelly Ivors ◽  
Wei Shi ◽  
D. M. Benson
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Cellulase Activity ◽  
Enzyme Concentration ◽  
Disease Suppression ◽  
In Vitro Assays ◽  
Infested Soil ◽  
Phytophthora Root Rot ◽  
Standard Curve

Wood-based mulches are used in avocado production and are being tested on Fraser fir for reduction of Phytophthora root rot, caused by Phytophthora cinnamomi. Research with avocado has suggested a role of microbial cellulase enzymes in pathogen suppression through effects on the cellulosic cell walls of Phytophthora. This work was conducted to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml–1 or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10 to 50 U ml–1 significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml–1. In a lupine bioassay, cellulase was applied to infested soil at 100 or 1,000 U ml–1 with three timings. Cellulase activity diminished by 47% between 1 and 15 days after application. Cellulase applied at 100 U ml–1 2 weeks before planting yielded activity of 20.08 μmol glucose equivalents per gram of soil water (GE g–1 aq) at planting, a level equivalent to mulch samples. Cellulase activity at planting ranged from 3.35 to 48.67 μmol GE g–1 aq, but no treatment significantly affected disease progress. Based on in vitro assays, cellulase activity in mulch was sufficient to impair sporangia production of P. cinnamomi, but not always sufficient to impact vegetative biomass.

scholarly journals Phytophthora mediterranea sp. nov., a New Species Closely Related to Phytophthora cinnamomi from Nursery Plants of Myrtus communis in Italy

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 682
Author(s):  
Carlo Bregant ◽  
Antonio A. Mulas ◽  
Giovanni Rossetto ◽  
Antonio Deidda ◽  
Lucia Maddau ◽  
...  
Keyword(s):  
New Species ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Colony Growth ◽  
Phytophthora Species ◽  
Maximum Temperature ◽  
Pathogenicity Test ◽  
Forest Nurseries ◽  
Collar And Root Rot ◽  
A New Species

Monitoring surveys of Phytophthora related diseases in four forest nurseries in Italy revealed the occurrence of fourteen Phytophthora species to be associated with collar and root rot on fourteen plants typical of Mediterranean and alpine regions. In addition, a multilocus phylogeny analysis based on nuclear ITS and ß-tubulin and mitochondrial cox1 sequences, as well as micromorphological features, supported the description of a new species belonging to the phylogenetic clade 7c, Phytophthora mediterranea sp. nov. Phytophthora mediterranea was shown to be associated with collar and root rot symptoms on myrtle seedlings. Phylogenetically, P. mediterranea is closely related to P. cinnamomi but the two species differ in 87 nucleotides in the three studied DNA regions. Morphologically P. mediterranea can be easily distinguished from P. cinnamomi on the basis of its smaller sporangia, colony growth pattern and higher optimum and maximum temperature values. Data from the pathogenicity test showed that P. mediterranea has the potential to threaten the native Mediterranean maquis vegetation. Finally, the discovery of P. cinnamomi in alpine nurseries, confirms the progressive expansion of this species towards cold environments, probably driven by climate change.

Variability and inheritance in macadamia progenies to Phytophthora cinnamomi and P. multivora the causal agents of root rot and stem canker

2021 ◽  
Author(s):  
Olumide S. Jeff-Ego ◽  
Andre Drenth ◽  
Bruce Topp ◽  
Juliane Henderson ◽  
Olufemi A. Akinsanmi
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Stem Canker

CHEMICAL CHARACTERISTICS OF A NATURAL SOIL LEACHATE FROM A HUMIC PODZOL

1969 ◽  
Vol 49 (1) ◽  
pp. 151-158 ◽  
Author(s):  
M. Schnitzer ◽  
J. G. Desjardins
Keyword(s):  
Organic Matter ◽  
Fulvic Acid ◽  
Water Solubility ◽  
Structural Features ◽  
Natural Soil ◽  
Complexing Agent ◽  
Soil Leachate ◽  
Nitrogenous Compounds ◽  
Free Weight ◽  
Metal Organic

A leachate, collected in the field in a lysimeter placed between the Ae and Bhf horizon of a Humic Podzol in Newfoundland, was analyzed by chemical and spectroscopic methods.About 87% of the dry, ash-free weight of the leachate was fulvic acid, the remainder consisting mainly of polysaccharides and nitrogenous compounds. A comparison of the analytical characteristics of the purified leachate with those of extracted and purified Podzol Bh fulvic acid showed that the main structural features of the two materials were very similar. Judging from its high contents of oxygen-containing functional groups and from its water solubility, the organic matter in the leachate had all the characteristics of an efficient metal–complexing agent, capable of playing a significant role in metal–organic matter interactions in soils.An organic matter–silica sediment was isolated from the leachate, consisting of 47.6% organic matter and of 52.4% of almost pure SiO2∙nH2O. The organic matter in the sediment accounted for about 10% of the organic matter in the leachate. The isolation of the sediment suggests that investigations on interactions between compounds of silicon and humic substances deserve greater attention than they have so far received.

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