phytophthora lateralis

[ORclimber]

Has anyone tried to treat Phytophthora in Port Orford cedar?

Here's an abstract from '97 July J of A.

CONTROL OF PHYTOPHTHORA LATERALIS ROOT ROT OF LAWSON CYPRESS WITH ENTEROBACTER AEROGENES

by Raj Utkhede, Bill Stephen, and Stephen Wong

Abstract. The biological agent strain B8 of Enterobacter aerogenes, applied in June of 1992, 1993, 1994, and 1995 as a soil drench at 6.7 x 109 colony forming units per tree, was evaluated for control of Phytophthora lateralis root rot of Lawson cypress (Chamaecyparis lawsoniana) trees. The test was conducted under field conditions in the city of Vancouver, British Columbia, on naturally infected Lawson cypress trees. Based on four years of observations, strain B8 of E. aerogenes controlled the disease and increased the growth of trees. This study showed the potential of strain B8 of E. aerogenes for biological control of root rot of Lawson cypress trees.

 

[ORclimber]

Subdue Max is also labeled for control of Phytophthora. Anyone tried it?

 

[ORclimber]

More potential possibilities Metalaxyl and fosetyl.

from Stratageis to Control Phytophthora Cinnamonni Root Rot of Avacodo by J. A. Mange.

Two fungicides have been very successful at reducing avocado root rot in many areas of the world (Coffey,1987, 1992; Erwin and Ribeiro, 1996) . Metalaxyl (RidomilR) is highly soluble, moves readily in soil and is absorbed readily by avocado roots. It may be applied as a granular, a drench or injected into the irrigation water. A single application of metalaxyl will provide 3 months of control. Some resistance to metalaxyl has been found in some Phytophthora spp. and rapid soil degradation may occur in some soils, although uptake of the material by roots should occur well before degradation begins. Metalaxyl will kill active Phytophthora in the soil, but it is not capable of destroying all the Phytophthora inoculurn. The other fungicide is fosetyl-AI (AlietteR) or potassium phosphonate which breaks down into the active ingredient phosphorous acid. They appear to be superior to metalaxyl when applied to mature trees in California (Coffey, 1992). This fungicide is translocated both upward and downward in the plant, although the upward movement is much stronger. Fosetyl-AI or potassium phosphonate can be applied as soil drenches, foliar sprays, trunk paints, trunk injections or injected into the irrigation water. All methods are effective if used properly, but local preferences indicate some methods work better than others under certain growing conditions. Foliar sprays require more chemical be applied and this method may not be practical on steep slopes. Soil applications require that roots be available for uptake of the material, so trees in advanced stages of root rot are difficult to rejuvenate using soil applications. Heavy clay soils may also impede the uptake of this material from soil. Trunk paints are more effective for treating trunk lesions, and it is often difficult for enough fungicide to be absorbed through the bark to effectively rejuvenate the roots. Injections are often the best way to rejuvenate root-rotted trees, but there is concern in many countries that wood decay organisms may invade the injection holes or that the intense, brown stain in the avocado wood surrounding injection holes may damage the trees. There is little evidence to support either of these concerns. Fosetyl-Al should be buffered with potassium hydroxide before it is injected into trees. The correct timing for treatment is during active root growth since the material moves toward areas in the tree with active growth. Since root flushes generally follow foliage flushes, these fungicides should be added when the foliage flush is three-quarters complete. There are generally two root flushes per year—one in the spring and the other in the late summer or fall. Fosetyl-AI has little direct effect on soil populations of Phytophthora, but rather it seems to function mainly by increasing the resistance of avocado roots to infection, which indirectly lowers the soil populations of P. cinnamomi. A single application of Fosetyl-AI or potassium phosphonate will provide 3 - 4 months of control. For both fungicides, growers should heed label directions because rates, products and methods of application may vary for each country in which avocados are grown.

 

[Guy Meilleur]

Natural or synthetic?

Of the 2 kinds of treatments that contorl Phytophthora, I'd go with the natural. Once Enterobacter or Heterobasidion have colonized the soil around the plants, there should be no room for phytophthora to invade.

with the toxics like Subdue, the soil is pretty much sterilized and P can reinvade once the toxic breaks down.

Enterobacter is sold as Compete by PHC Inc. I just started trying it so my info that it works is 2nd hand from another tree guy, and reading the study you posted. Enterobacter is a common microbe in healthy soil, so my strategy would be to rake away mulch, rake away soil down to the roots and replace it with good soil mixed with compost.

The compost can be injected by aerating with a pick and stuffing the holes with it. Also. Phosphite is a proven product to control P, I would use it in concert with the soil inoculation. If the 2 yellowing plants look like they'll die, I'd rip em out and focus my efforts on that end of the row.

 

[ORclimber]

Thanks Guy. Your answers lead to more questions.

Enterobacter isn't listed as being in Compete Plus. I posted a question on PHC's forum asking about using Compete to displace Phytophthora. I hope they can provide some research to back up the products effectiveness.

This isn't the Heterobasidion you're refering to is it? http://www.pfc.forestry.ca/diseases/CTD/Group/Root/root3_e.html

Why not kill the soil and immediatly pump it back up with the good stuff? Beneficials, Compost tea, and mulch. I'm not nutty enough to try that without the research to back it up.

 

[Guy Meilleur]

Sorry it's Trichoderma not Enterobacter that's proven to work against P. PHC Inc. is wary of making false claims so they will NOT say it works on infected trees, only to use it as a preventative. (At least that's what they told me). So inoculating the soil around the trees that don't show symptoms is safe to recommend, imo.

Re kill-then-pump-up, I wonder about residual effects of Subdue, etc.

 

[ORclimber]

Thanks Guy.

That phosphonate appears to be THE stuff for fighting Phytophthora. Thank you Australia.

Phosphonate for the fight in the tree and PHC Compete for the soil is my current plan. I'll present the facts(as vague as they are) and let the client decide.

There isn't any direct research showing that phosphonate will control phytophthora in Port Orford Cedars. The product available for SOD lists conifer plantings on the label, so there is a loophole to use it on Port Orfords.

I fired an e-mail to the PNW research station inquiring about any current research using phosphonate on Port Orfords. Hopefully with all the $ being spent on SOD something more concrete will cross over.