Phytophthora treatments--resources

[treeseer]

Aside from phosphite, many other treatments can be applied. Sifting through the list in Sinclair's text on Diseases of Trees, downloading these:

 

https://www.dropbox.com/sh/b5hnt9tjp2ot0vq/o3S9V1lOUa?n=15346635

[Gary Prentice]

:thumbup:Thanks for posting Guy. I've just received my copy

[treeseer]

A brief look at treatment options, via Sinclair:

 

p. 354

"The nuclear condition of somatic structures and all mature spores is diploid (or polyploid in some strains). Spores of all types require free water for germination."

 

p.356

"Wounds and intact succulent plant parts such as shoot or root tips are suitable for infection. On reaching a suitable surface, a zoospore rounds up, loses its flagella, secretes a cell wall (encysts), and produces a germ tube that penetrates the plant and gives rise to mycelium"

 

"The generalists that cause much damage to trees and shrubs are, except for P. ramorum (discussed in a later section), soilborne organisms whose activities tend to be favored by wet sites - soils along watercourses or that have impeded internal drainage or are irrigated by flooding. Such conditions not only promote the pathogens' infection. Roots stressed by oxygen deficiency in waterlogged soil exude more amino acids and other substances attractive to zoospores, and their resistance to pathogens is impaired. Saline soil or previous water shortage also lowers plant resistance."

 

"Once established in a new location, even though the site might be seasonably dry, a Phytothera may persist and cause damage for years unless the microbial population of the site suppresses it through competition and antagonism."

 

"Managmetn of Phytophthora disease is difficult. Awareness of the need usually begins with a disease outbreak. Disease spread can be retarded by restricting site disturbance and movement of plants, soil, water, and people. Outbreaks in plantations, orchards, and nurseries can be avoided or minimized by site selection to avoid wet or poorly drained sites and/or by improving drainage, ensuring clean irrigation water, and utilizing drip or trickle irrigation rather than overhead or flood irrigation."

 

"Disease control with pathogen-suppresive rooting substrates and fungicides is possible in nurseries. Phytophthera activity in soil can be suppressed somewhat by calcium fertilizers or soil amendment with gypsum. Plants in nurseries, orchards, and landscapes can be treated prophylactically with certain fungicides and resistance-inducing chemicals such as potassium phosphate. Expansion of basal cankers on a diseased tree can sometimes be halted by heat or surgery. Solar heating of soil beneath clear plastic can suppress Phytophtoras in regions of warm climate.

 

p.362

 

"Surgery and heat treatment to halt the enlargement of basal cankers on orchard and shade trees have been demonstrated but are not often used because they are laborious, destroy healthy tissues around cankers, and may fail to halt tree decline. Some orchardists utilize resistance-inducing or Phytophthora-suppresive fungicides to limit damage."

 

p.364

 

 

"P. cinnamomi attacks the small absorbing roots and in many hosts also invades larger roots or the butt and mainstem, growing mainly in the inner bark and cambial zone. It derives nourishment from recently killed as well as living tissues, and it reproduces in the dead tissues."

 

"P. cinnamomi in requires warrm, wet soil for significant pathogenic activity. It does not persist where soils regularly freeze deeply in winter."

 

"The interval between infection and sporulation of P. cinnamomi is only a few days, so disease can increase explosively if warm infested soil is flooded and waterlogged. Microbial populations influence the conduciveness or suppresiveness of soils to disease caused by P. cinnamomi."

 

"In one study with P. cinnamomi in Rhododendron obtusum (Hinodegiri azalea), plants that were deliberately innoculated before outplanting in a landscape situation failed to thrive, and many died. In contrast, similarly inoculated plants that were treated with fungicides before outplanting performed normally."

 

"Damage by P. cinnamomi in orchard and nursery situations can be lessened somewhat by amending surface soil with gypsum (hydrated calcium sulfate). This substance and other calcium compounds interfere with sporangium formation and zoospore function and thus suppress infection."

 

p. 366

 

"Ectomycorrizal fungi protect some pine rootlets from P. cinnamomi, but this is not sufficient to prevent littleleaf disease on soils with conducive physical characteristics. The disease still occurs, although the magnitude of the problem has diminished. This change reflects tree planters' recognition and avoidance of high-risk soils, replacement of susceptible trees with tolerant ones on many sites, and improvement of soil structure and microbial activity during several decades of forest regrowth."

 

"Damage in nurseries can be minimized by using pathogen-suppresive container mixes; irrigating with pathogen-free water; covering soil in container mixes; covering soil in container nurseries with woven ground fabric, gravel, or coarse mulch that prevents transfer of pathogens in splashing or running water from soil into pots; and *adding calcium chloride or calcium nitrate to water or liquid fertilizer. Calcium ion (CA++) at nutritional concentrations was shown to cause P. nicotianae zoosporess to encyst without contacting susceptible tissue and to interfere with infection."

[Tony Croft aka hamadryad]

"Once established in a new location, even though the site might be seasonably dry, a Phytothera may persist and cause damage for years unless the microbial population of the site suppresses it through competition and antagonism."

 

good on you for taking the time to actually hav a root about after my little prod the other day! The statement above is in my opinion the right path, in time this avenue may prove highly beneficial in limiting damage by Phytopthoras.

[treeseer]

good on you for taking the time to actually hav a root about after my little prod the other day!

 

I hear and obey, o Mighty Masta Phi Slamma Hama!

 

"The statement above is in my opinion the right path, in time this avenue may prove highly beneficial in limiting damage by Phytopthoras.

 

Been proven for a long time.

 

You did see the part about surgery and heat, right?