TWO DISEASES ARE NOW WIDESPREAD IN WHEAT

Press, Volume XCVIII, Issue 29070, 5 December 1959, Page 8

TWO DISEASES ARE NOW WIDESPREAD IN WHEAT

At present only two diseases are widespread in wheat crops in Canterbury. This has been shown by a survey of crops carried out recently by Dr. Harvey Smith, a plant pathologist of the Plant Diseases Division of the Department of Scientific and Industrial Research, and Mr Graham Wright, a cereal breeder of the Crop Research Division of the same department. These are mildew and yellow-dwarf vifus, each of which was found in two-thirds of the crops examined.

The virus was most common in North Canterbury, where about one quarter of the crops had sufficient infection to reduce yields. Mildew, however, is not likely to do appreciable damage this season. In South Canterbury, Aotea crops had more mildew than Arawa, and less virus. Three diseases were found in about a quarter of the crops; Septoria leaf blotch (which was common when Cross 7 was widely grown), loose smut, and leaf rust. None of these was of practical importance, but there were two other diseases which may produce considerable damage before harvest. In one crop seen there was a heavy infection of take-all (this was in a paddock

carrying wheat after wheat), and in one crop in North Canterbury stem-rust infection was already moderately severe on the upper leaves. Although stem rust has been seen in only a few crops, there is plenty of time for tne disease to spread, and the weather over the next month will affect both the amount ol spread and the damage produced.

Army Worms In JJorth Canterbury army worms were seen in half the crops in small numbers, and no doubt farmers will be examining their wheat regularly to make sure of spraying for army-worm control as soon as it becomes necessary. Little damage has been caused by Hessian fly, leaf miners, or stem weevil. Crops on the lighter soils in Ashburton district are coming on well, but in North Canterbury some wheat has been affected by the dry conditions. Here again, however, it is too early to say what the final effects will be. as some crops which now look stunted could recover fairly well if enough rain falls in the next few days. It would be rash to predict yields at this stage, but it is fair to say that most crops are looking extremely well.