Foliar Disease Pressure Remains Light Across State According to OSU Plant Pathologist Bob HungerFri, 29 Mar 2019 16:31:22 CDT
Oklahoma State University Extension Plant Pathologist Dr. Bob Hunger, released this week his latest wheat disease report for Oklahoma. His and others’ observations made while travelling across the state and region this past week are recorded in his statements below.
“Foliar diseases continue to be light across Oklahoma. Gary Strickland (Extn Educator; southwest OK) indicated he is still seeing only light and scattered leaf rust pustules on senescing lower leaves. He has not seen any powdery mildew or leaf spot diseases but has seen some low numbers of winter grain mites and heard of one field where the numbers were high and the field was sprayed. Around Stillwater, I have seen much the same, that is, no powdery mildew or stripe rust and only scattered, ‘old’ leaf rust pustules on lower senescing leaves. However, in addition to the leaf rust I have observed bird cherry oat aphids in older wheat (growth stage 7 to 8 ((two nodes visible to flag leaf just appearing)) as well as some septoria on lower leaves. David Nowlin (Extn Educator; Caddo County) also has indicating having observed septoria as indicated by his email of 25-Mar where he indicated, ‘I can see what looks like pycnidia on bottom leaves of wheat West of Anadarko, I assume it’s Septoria leafspot- it’s the only disease I am seeing.’
“In Texas, Dr. Amir Ibrahim (Small Grains Breeder/Geneticist, Texas A&M University) reported on 18-March that in a large wheat nursery near Castroville, TX (southern Texas near San Antonio) that,
“’Stripe rust (caused by Puccinia striiformis f.sp. tritici.) is drying up on both classes (hard red and soft red winter wheat). Leaf rust (caused by Puccinia triticina Erikss.) is uniform across the field and moving up the canopy with some susceptible lines showing 100S reaction in the upper canopy. We have not seen this high leaf rust severity around mid-March in a long time.’
“The observations in Oklahoma coupled with the report from Texas indicate to me that leaf rust is going to be the rust of concern this year in Oklahoma. Of course, that will still require the right weather (rains/dews and moderate temperature), but inoculum for leaf rust is being produced in southern Texas that should spread northward if weather allows. Plus, there is inoculum that survived in Oklahoma to also promote leaf rust with favorable weather. In contrast, stripe rust inoculum appears to be sparse.”
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