[compost_tea] Strike Rust
Elaine,
I contacted Bruce Elliot via email re stike rust but as yet I have not had =
a reply.
You say in your email that there have been "..excellent results..." using =
CT on Wheat in Nebraska to reduce rust disease.
We are going to be using CT this year to reduce Srike Rust in Wheat in West=
ern Australia. We will be using fungal dominated CT. I am assuming that we =
will require fungal diminated CT to out compete the Srike Rust (being a pat=
hogenic fungus)??
I am also assuming that we will need to cover say 70% of the leaf surface a=
rea (same as in grapes) in order to out compete the Strike Rust. Looking f=
orward to the microscope to assess this!!
As per info below it would seem that coverage of the wheat seedling is ess=
ential (our autumn/early winter) when warmer temps favour infection. Also s=
pring time when things warm up would be another important time to get the C=
T on the plant. (we grow winter wheat). We will also be spraying CT on to s=
tubbles prior to turning in to get an inoculation of beneficials into the s=
ystem.
Are we on the right track??
The following is some info on rust.
PP589 (revised), July 2002
Marcia McMullen, Plant Pathologist, NDSU Extension Service
Jack Rasmussen, Plant Pathologist, Agricultural Experiment Station
The Disease The following factors must be present for wheat leaf rust infec=
tion to occur: viable spores; susceptible or moderately susceptible wheat p=
lants; moisture on the leaves (six to eight hours of dew); and favorable te=
mperatures (60 to 80 degrees Fahrenheit). Relatively cool nights combined w=
ith warm days are excellent conditions for disease development.
Under favorable environmental conditions, rust spores germinate and penetra=
te into the wheat leaf. The fungus obtains nutrients from the wheat leaf, a=
nd within a week to 10 days the fungus produces more spores, which erupt th=
rough the leaf surface. These newly produced spores are wind-blown to other=
wheat leaves or fields.
Resistant and susceptible wheats react differently to infection. If a varie=
ty is resistant, a reaction develops within the leaf which kills or retards=
the fungus, and the infection is stopped. Resistant varieties may develop =
yellowish-white "flecks" at the site of spore penetration (Figure 1). Moder=
ately resistant varieties develop small reddish-orange pustules surrounded =
by a yellow-white halo (Figure 1). Susceptible varieties do not have the ab=
ility to retard fungal growth; the fungus grows extensively and produces re=
latively large pustules that may produce about 1,000 spores daily, each one=
of which is capable of reinfecting wheat (Figure 1). The outcome of a 10-d=
ay repeating cycle is the formation of many spores during the growing seaso=
n, and these spores can move great distances on wind currents (Figure 2). T=
herefore, this disease can increase rapidly and epidemics may occur wheneve=
r susceptible varieties are grown and weather conditions are favorable for =
rust development.
The extent of yield losses caused by leaf rust depends on the severity and =
duration of infection. The greatest losses occur if the crop is severely ru=
sted from the seedling stage to maturity. .
Received on Wed Feb 26 2003 - 11:14:34 EST
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