Oakes Irrigation Research
Site
Carrington Research Extension Center * North Dakota State University
P.O. Box 531, Oakes, ND 58474-0531, Voice: (701) 742-2189, FAX: (701)
742-2700, email: rgreenla@ndsuext.nodak.edu
Nightshade
Control in Pinto Bean with
Herbicides Applied at Reduced Rates
Chad Ringdahl and Calvin Messersmith
Plant Science Department, NDSU
This experiment was conducted in 1999 and 2000 near Oakes, ND, to evaluate pinto bean injury and seed yield and nightshade control resulting from herbicides applied at reduced rates and multiple times. "Frontier" pinto bean was planted 15 May 2000, in 30-inch rows at a depth of 1 inch. First applications of two- and three-time treatments were applied to nightshade in the two- to four-leaf stage, and pinto bean was in the unifoliolate to one-trifoliolate leaf stage. The second treatments of the two-time treatments were applied when 90% of nightshade present were in the four-leaf stage. Second treatments of the three-time treatments were applied when 90% of nightshade present had two to four leaves, and the third treatment was applied when 90% of the nightshade had five to six leaves. Single treatments were applied when nightshade had six to eight leaves.
Hairy nightshade was the predominant species in the experiment, although black and eastern black nightshade were also present. Treatments were applied with a bicycle-wheel-type plot sprayer delivering 8.5 gpa at 40 psi through 8001 flat-fan nozzles spaced 20 inches apart to a 7 ft wide area the length of 10 by 20 ft plots. The experiment was in a randomized complete block design.
Cobra applied three times caused greater visible pinto bean injury than all other treatments, except Blazer applied three times. Cobra and Blazer tended to injure pinto bean more than Raptor, Pursuit, or Reflex. However, pinto bean recovered from Raptor, Pursuit, and Reflex injury, and seed yield was not reduced significantly compared to most treatments, except the highest yields occurred with Raptor applied once and Reflex applied three times. The handweeded check experienced a severe infection of sclerotina, which reduced yields as compared to herbicide-treated plots. Pinto bean in the herbicide-treated plots had a less dense canopy, which apparently had greater air movement and reduced humidity to reduce disease infection.
Nightshade control was generally good for all treatments evaluated in 2000. However, Cobra and Blazer applied twice provided significantly less nightshade control than Raptor and Pursuit treatments. Also, full-rate and three-time treatments of Cobra and Blazer provided good nightshade control. The rate of each herbicide for the two-time treatments may have been too low to control the nightshade present. For the 1999 experiment, all treatments provided 98% or better nightshade control (data not presented). However, nightshade densities were low in 1999 compared to 2000; thus, more reliable data based on nightshade densities were obtained in 2000.
Treatments containing Raptor and Pursuit all provided good season-long control of nightshade, suggesting that these two herbicides are viable nightshade control options in pinto bean. Reflex applied two and three times provided excellent nightshade control, and pinto bean from these plots were among the highest yielding treatments in the experiment. Thus, Reflex has potential as an acceptable herbicide for nightshade control in pinto bean. Based on data from this experiment, Raptor, Pursuit and Reflex may be applied at reduced rates to achieve adequate nightshade control, and pinto bean had good tolerance to all three herbicides. Cobra and Blazer injured pinto bean, which was apparent in yield reduction compared to many other treatments.
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Table 44. Effect of five POST herbicides applied one, two or three times on visible injury, nightshade control and pinto bean seed yield (averaged over 1999 and 2000).
| Herbicide | Rate of product | Crop injury | Nightshade control | Seed yield |
| fluid oz/acre | % | % | lbs/acre | |
| Raptor | 4 | 4 | 97 | 1980 |
| Raptor | 1.5 fb1 1.5 | 3 | 98 | 1840 |
| Raptor | 1 fb 1 fb 1 | 5 | 95 | 1800 |
| Pursuit | 2 | 4 | 94 | 1850 |
| Pursuit | 0.75 fb 0.75 | 3 | 92 | 1690 |
| Pursuit | 0.5 fb 0.5 fb 0.5 | 3 | 97 | 1700 |
| Blazer | 16 | 6 | 80 | 1500 |
| Blazer | 6.4 fb 6.4 | 5 | 68 | 1370 |
| Blazer | 4 fb 4 fb 4 | 8 | 96 | 1500 |
| Reflex | 12 | 4 | 74 | 1400 |
| Reflex | 4.8 fb 4.8 | 5 | 86 | 1800 |
| Reflex | 3.2 fb 3.2 fb 3.2 | 4 | 97 | 2030 |
| Cobra | 6 | 7 | 94 | 1260 |
| Cobra | 2 fb 2 | 5 | 51 | 950 |
| Cobra | 1.5 fb 1.5 fb 1.5 | 11 | 92 | 1340 |
| Raptor + Blazer | 0.5 + 4 fb 0.5 + 4 | 6 | 77 | 1720 |
| Pursuit + Blazer | 0.5 + 4 fb 0.5 + 4 | 5 | 86 | 1590 |
| Raptor + Reflex | 0.5 + 4 fb 0.5 + 4 | 4 | 89 | 1870 |
| Pursuit + Reflex | 0.5 + 4 fb 0.5 + 4 | 4 | 84 | 1740 |
| Raptor + Cobra | 0.5 + 1.5 fb 0.5 + 1.5 | 6 | 90 | 1650 |
| Pursuit + Cobra | 0.5 + 1.5 fb 0.5 + 1.5 | 6 | 82 | 1670 |
| Untreated | 0 | 0 | 0 | 1170 |
| Handweeded | 0 | 0 | 100 | 1190 |
| LSD (0.05) | 3 | 23 | 550 | |
1 fb, "followed by" for split-applied treatments.
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Go to Oakes Irrigation Research Site Weed Control Studies page
Go to Oakes Irrigation Research Site 2000 annual report