The moist spring in many areas has created conditions ripe for cereal leaf disease if rain and high humidity continue into summer.
Producers with winter wheat and those who got their cereals in before it started to rain should already be looking for signs of leaf disease when scouting fields, said Andy Tek-auz, head of cereal leaf disease research at Agriculture Canada’s cereal research centre in Winnipeg.
If you are about to seed, avoid planting wheat or barley on stubble from the same crops, choose a variety less susceptible to the diseases, and use clean seed treated with an appropriate fungicide.
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“Any crops in the ground now or in soon should come up fairly well and be nice and lush. Any conditions that lead to a good crop are the same conditions that are ideal for development of the disease,” said Myron Kopec, development and technical services manager, Novartis Crop Protection.
Tekauz said early infections of leaf diseases such as net blotch, scald, septoria leaf and glume blotch and tan spot can damage the lower leaves, weakening and possibly killing the plants.
“The second thing that can happen is that the infected lower leaves can provide a source of the disease for later on in the season when we get some additional wet weather. You see the disease moving up the plant towards the upper leaves, particularly the flag leaf, which is the one we want to protect.”
Penny Pearse, plant disease specialist with Saskatchewan Agriculture, said the weather during the growing season will determine whether the disease pathogens in the stubble will cause a problem. Moisture and humidity will increase the chance of a disease problem.
“We always encourage scouting. But this year, if the diseases are to a level that would warrant a fungicide application, with the price of grain the way it is, it might not be worth it to spray even if it is knocking back your yield.”
Preserve quality
Kopec said each farmer’s situation will be different, but he cited an example of a barley crop that appears it will go malt. The foliar fungicide should preserve the malt quality and help the yield by about 10 percent.
Three fungicides are registered for control of fungal cereal leaf disease. Propiconazole under the trade name Tilt is a broad spectrum systemic fungicide registered for use on wheat, barley and oats; mancozeb (Dithane DG) is a contact fungicide registered for use on wheat; chlorothalonic (Bravo) is a contact fungicide for use on wheat.
“The ideal time to spray Tilt is at the early flag leaf so they have to be scouting before that,” Kopec said.
Up to half of the final yield of a wheat crop depends on the health of the upper leaves, particularly the flag leaf or in barley, the top two leaves.
Kopec said leaf area affected by the disease no longer produces food for the plant. Spraying will not bring the leaf back into production so it must be sprayed to prevent damage.
Rusts are also leaf diseases, but they do not overwinter here and must blow in from the United States.
