Wild Garlic Control in Winter Wheat with Peak, 1996.

Fall-applied Peak and Harmony Extra caused a reduction in wheat stand and a reduction in wheat yield compared to the nontreated check and spring-applied Peak. Spring-applied Peak was more effective than when it was applied in the fall in reducing wild garlic aerial bulblet number in the harvested wheat.

I. INTRODUCTION:

Wild garlic control in winter wheat was a major production problem until the commercialization of Harmony Extra. This study was conducted to evaluate winter wheat tolerance and wild garlic control efficacy with the new sulfonylurea herbicide Peak.

II. HERBICIDES EVALUATED:

      Banvel 4 EC
      Harmony Extra 75 WG
      Peak 57 WG

III. ABBREVIATIONS USED:

      ALLVI: wild garlic
      DCSOY: doublecrop soybeans
      GLXMA: soybeans
      /KG: per kilogram (2.2 lb)
      LVS: leaves
      TRZAW: winter wheat

IV. RESULTS AND DISCUSSION:

Wild garlic control based on visual injury ratings and number of aerial bulblets per kilogram (2.2 lb) of wheat grain are presented in the attached table. Also, the attached table includes data on wheat stand (visual rating), percent stunt, test weight, and yield.

Based on past experience, visual ratings of wild garlic control is a very imprecise type of evaluation because of the difficulty of seeing the garlic plants through the dense wheat canopy. In this study, Peak plus X-77 or crop oil concentrate fall-applied controlled wild garlic 74 to 80%. The number of aerial bulblets per kg (2.2 lb) was 54, 6, and 99 with Peak at 0.50 and 0.75 oz/A product with X-77 and with 0.50 oz/A plus crop oil concentrate, respectively. This clearly indicated that Peak at 0.75 oz/A product was more effective in reducing wild garlic bulblets than the 0.50 oz/A rate. When Peak was spring-applied, reduction in aerial bulblets was even more dramatic, with only 2, 0, and 0 bulblets with 0.50, 0.75, and 1.0 oz/A rates. Fall-applied Harmony Extra did not reduce garlic bulblets compared to the nontreated check.

The wheat stand in 1996 (fall 1995 planting) was influenced by low soil moisture in 1995, which resulted in slow emergence and limited growth in spring 1996. Additionally, following renewed growth in spring 1996, low temperature on Febr. 16 (11F), Febr. 31 (16F), March 8 (11F), March 22 (22F), March 26 (20F), and April 9 (25F) caused substantial injury to the wheat. This injury reduced wheat stand in all plots, but especially in those treated with Peak and Harmony Extra in fall 1995. Spring-applied Peak did not reduce wheat stand compared to the no herbicide plots. Wheat growth was stunted substantially in all plots, even those where no herbicide was applied.

There was little difference in wheat test weight between the several treatments. Wheat yield was decreased with fall-applied Peak at 0.50 oz/A and with Harmony Extra. This likely was a reflection of the reduced wheat stand and stunting that had been observed. 

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