Kent McKay

Area Extension Agronomist/Cropping Systems

North Central Research Extension Center, Minot, ND

701-857-7682

e-mail: kmckay@ ndsuext.nodak.edu

There were over 50,000 acres of chickpeas planted in North Dakota and Montana in 2001, which is an increase from a few thousand in 1998. In the Canadian prairies, acres have surged to 1.2 million, up from less than 10,000 acres in 1995. Ascochyta blight is a major disease in chickpea which limits production to drier climates. In the past two years ascochyta blight has caused major losses in yield and many producers have suffered large economic losses in the United States and Canada. In 2000 and 2001, ascochyta inoculum traveled very long distances across the entire growing region where chickpea had been previously grown without any major ascochyta problem. In 2001, western North Dakota had below normal precipitation during the growing season and areas of Montana and western Saskatchewan had drought conditions and still ascochyta blight caused devastating financial losses. This has growers very concerned with raising chickpeas in 2002.

As of December 20, 2001, only Bravo Ultrex and Bravo Weatherstick Zn are registered for use in chickpea in the U.S. and Canada. In 2001, Quadris, by Syngenta, received a crisis exemption for use in the U.S. and Canada. Quadris is currently not registered in the U.S. or Canada; however, registration is pending for the use in 2002 in both countries. BAS 500 or Headline, by BASF, is currently not registered; however, registration is pending for use in 2002 in both countries.

In 2001 fungicide studies were conducted at Minot, Williston, Carrington, and Hettinger, ND to evaluate fungicides, application rates, and timings for control of ascochyta blight in chickpea. The following research results are from the studies conducted at Minot and Williston. Sanford chickpea was planted April 27 at Minot and Dwelley chickpea was planted May 14 at Williston. At both locations, plants in the untreated plots had died from ascochyta by late July. Bravo alone gave poor control of ascochyta blight resulting in very low yields and poor seed quality. These results indicate that once the disease is present and conditions are favorable for the spread of the disease, Bravo alone will not give sufficient control of ascochyta blight.

At Minot, Quadris applied twice controlled ascochyta through July; however, disease pressure increased in August reducing yields and overall quality. Quadris followed by Bravo followed by Quadris did not give sufficient control of ascochyta compared to two applications of Quadris. Bravo applied prior to flowering, when ascochyta blight was first detected, followed by two applications of Quadris gave season-long control of ascochyta. The high rate of BAS 500 (Headline) applied twice had significantly lower disease ratings and had significantly higher yields than the low rate of BAS 500 or Quadris applied twice.

At Williston, Bravo applied prior to applications of Quadris had significantly higher yields and significantly better quality than Bravo applied between applications of Quadris. Two applications of Quadris had significantly higher yields than any treatment where Bravo was applied alone or between Quadris applications. The higher rate of BAS 500 applied twice had significantly higher yield than the low rate. The higher rate of BAS 500 and Quadris applied twice gave good control of ascochyta and had similar yields and quality. Research results indicate that if Bravo is going to be used to control ascochyta, it has to be applied prior to disease development and then followed by an application of Quadris or BAS 500.

Field pea and chickpea are very poor competitors with weeds at all stages of growth. Annual weeds that emerge early in the growing season including kochia, winter annuals, Russian thistle, wild buckwheat, and wild oat are the most competitive with field pea and chickpea. Weeds such as kochia, Russian thistle, and wild buckwheat can cause harvest problems with fields that are intended to be straight combined.

Field pea weed control studies conducted by Brian Jenks, North Central Research Extension Center, Minot, ND in 2001, indicated that imazamox caused yellowing and slight stunting within three days after application, but by mid-season, the crop had generally recovered. Sulfentrazone caused very little visible crop injury and did not reduce crop stand. Herbicide treatments with Imazamox, Bentazon, Sulfentrazone, Trifluralin, and Sethoxydim increased pea yields 250-800 lb/A compared to the untreated check. Similar weed control studies were conducted with sulfentrazone in chickpea. Chickpea demonstrated good to excellent tolerance to sulfentrazone at Minot and Williston, North Dakota and Sidney, Nebraska. Whether applied under a conventional tillage system or no-till system, crop densities were similar to the untreated. These results agree with previous work in 1999 and 2000. Weed control studies indicate Sulfentrazone has given excellent control of kochia and Russian thistle when applied preemergnce in chickpea and field pea. Sulfentrazone has also given good suppression of wild buckwheat at the higher rates when applied preemergnce in chickpea and field pea. Sulfentrazone needs adequate rainfall for activation. North Dakota received a Section 18 exemption for sulfentrazone in chickpea and field pea in 2001.