LEAF RUST ON TRITICALE 



Low- level infections of leaf rust on triticale were recently observed on samples from 

 Pulaski -Alexander County. Only trace amounts of this rust developed in Texas and 

 Louisiana because of drier conditions. No control measures are suggested at this time. 



WHEAT LEAF RUST 



Blueboy wheat comprises approximately 70 percent of the 200 thousand acres of Georgia 

 wheat. For much of this, it will not be economical to harvest the grain this season 

 because of leaf rust damage. Other wheat varieties in southern areas are relatively 

 free of rust, including Wakeland and Blueboy II. Wheat leaf rust is light to moderate 

 in most other areas. It has reached as far north as Manhattan, Kansas. 



Leaf rust caused by Puccinia reaondita tritici produces small, round to oval, raised, 

 orange-yellow, dusty pustules on leaves of susceptible plants. Each pustule contains 

 thousands of summer spores (urediospores) . Rust usually begins on the lower leaves, 

 gradually progressing up the plant to the flag leaf. 



Arthur is moderately resistant, and Benhur is resistant to known Illinois strains of 

 the leaf rust fungus. In real problem areas, zineb fungicide is cleared for use on 

 wheat to prevent continued development of the disease. 



Use 2 pounds (1.5 pounds actual of 75 WP) of zineb per acre, at 7- to 10-day intervals 

 until the milk stage is reached. Do not graze treated areas. Dry weather usually 

 stops the progress of rust, making fungicides uneconomical. See Report on Plant Dis- 

 eases No. 108 (Revised), "Leaf Rust of Wheat," for further details. (Copies are avail- 

 able from the UI Department of Plant Pathology.) 



SPOT BLOTCH ON BARLEY 



Spot blotch, caused by Helminthosporium sativum has appeared on a few fields in south- 

 central Illinois. Yellow-leaf areas could be confused with the Barley Yellow Dwarf 

 Virus. Plants infected with spot blotch have chocolate -brown to black spots on leaves 

 and sheaths . Severely infected plants may be stunted and may have rotted crowns . Heads 

 may not emerge completely, and kernels fill poorly. The development of resistant va- 

 rieties is complicated because many races of the fungus exist in nature. See Report 

 on Plant Diseases No. US (Revised), "Spot Blotch, Net Blotch and Stripe Disease of 

 Barley." (Copies are available from Plant Pathology.) 



HELMINTHOSPORIUM LEAF SPOT ON WHEAT 



Cool, wet weather has favored development of Helminthosporium leaf spot on wheat and 

 forage grasses. Infection may occur almost any time during the growing season when 

 moisture remains on the leaves and leaf sheaths for at least several hours. It starts 

 on the lower leaves and will move upward to the younger leaves until checked by hot, 

 dry weather. 



Symptoms of Helminthosporium leaf spot vary according to the grass or wheat variety and 

 the Helminthosporium species involved. Generally, there are small, dark spots with 

 light yellow halos on susceptible plant leaves. Some lesions may merge to form streaks. 

 Others may extend to the width of the leaf, causing it to turn yellow or brown, wither 

 from the tip, and die. Di thane M 45 (or Manzate 200) is cleared for use on wheat in 

 heavily diseased fields. 



