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
EVALUATION
OF UAP CALCIUM COMPOUNDS
FOR WHITE MOLD CONTROL IN DRY BEAN,
2000
Patrick Gross, Department of Plant Pathology, NDSU
Cooperator: UAP
Table 73. Incidence and severity of white mold in dry beans when using UAP calcium compounds
A field trial was conducted at the Oakes Irrigation Research Site in Oakes, ND. Certified 'Buster' pinto bean was planted on 16 May in a field with soil type Emben loam. Bean seeds were planted in four-row plots with rows 30 in. apart. Each row was 17 ft long and a 3 ft buffer area was included at each end of each row. Seeds were planted at a depth of 1.5 in. and were spaced approximately 2.5 in. apart using John Deere flexiplanters fitted with standard hoppers. The planter was set to plant 85,000 plants/acre. At planting, soil moisture was high and soil temperature was 57F. Herbicides applied pre-emergence and post-emergence, along with cultivation and handweeding, provided good weed control. The plots were overhead sprinkler irrigated as needed. Calcium compound applications were made on 7 July (10% bloom) and 17 July at (100% bloom). Row closure was at 30% on 7 July and at 80% on 17 July. Calcium treatments were mixed in Fargo tap water (previously adjusted to pH 7.0 with HCl and/or NaOH) and applied within 2 hr of mixing. Sprays were applied using a CO2 powered backpack sprayer set to deliver 37 gal/acre at 35 psi. White mold incidence was evaluated on 3 and 10 August. Percent incidence was measured by placing a 10 ft rod arbitrarily between the center two rows of each plot. The rod was marked in 1 ft increments and the presence of disease was recorded if the imaginary visual plane at each mark passing through each row transected diseased material. Thus, 20 evaluations were made on each plot on each date. Percentage of infected sites was calculated. White mold severity was evaluated at the same site and time as incidence. Severity ratings were 0-5: (0 = 0%), (1 = 5%), (2 = 15%), (3 = 40%), (4 = 65%), (5 = 85%) infection. This rating scale is a modification of Horsfall-Barrat 11-point scale that recognizes exponential differences in severity evaluations. Means for severity were calculated only from plants with white mold. Plots were harvested on 23 Aug. All of the plants in 10 ft of the two center rows (=20 linear ft) of each plot were clipped from their roots and collected in burlap bags. Plants in bags were dried in forced air driers at 120 F for approximately 5 days. Beans were threshed using a belt thresher (Seedburo) set for beans. Final cleaning was with a seed cleaner and hand picking. Beans were weighed to the nearest 0.1 gram and moisture was determined on a Dickey-John moisture tester. Since the moisture on all samples was uniformly near 8%, the yields are reported as nonadjusted weights. Statistical analysis was made using the SAS ANOVA procedure. Alpha levels of 0.05 were used for all evaluations. LSD values were calculated and used for mean comparisons. The Duncan test was used for white mold severity analysis because of uneven sample size.
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Table 73. Incidence and severity of white mold in dry beans when using UAP calcium compounds. Oakes Irrigation Research Site, 2000.
| Treatment | Rate/acre | % Incidence1 | % Severity2 | Yield | ||
| Aug 3 | Aug 10 | Aug 3 | Aug 10 | |||
| --------------------- % -------------------- | lbs/acre | |||||
| Check | ------ | 45.0 | 73.8 | 17.5 | 31.0a | 2991 |
| Calcium 6% SGH3 | 1.5 gal | 38.8 | 52.5 | 14.4 | 31.3a | 3178 |
| Flo-Gyp 11%3 | 0.75 gal | 13.8 | 32.5 | 15.7 | 27.0a | 3037 |
| Topsin M 70WSB | 1.5 lb | 10.0 | 28.8 | 10.6 | 14.7b | 3592 |
| LSD (0.05) | 12.8 | 14.0 | ns | 286 | ||
1Incidence based on number of infected plants divided by total number of observations.
2Severity is based on average percentage disease of four replications.
3Calcium sprays were adjusted to 1500 ppm of total calcium.
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Soil conditions and temperatures were favorable for normal plant growth early in the season. Timely rains and irrigation helped continue normal plant growth in June. Plants began to flower around 5 July. Canopy was well filled within the rows at time of first spray application.
Plants continued to flower over a 3 to 4 week period during the summer. White mold from natural inoculum was not observed in the field by the second spray application on 17 July so a suspension of white mold spores was sprayed on the middle two rows of each plot after the spray application. White mold was observed in the field five days later. White mold was quite uniform across the field. White mold incidence was significantly reduced by the application of Flo-Gyp and Topsin compared to the untreated control on rating taken on 3 Aug. Plants treated with calcium and Topsin reduced white mold incidence significantly on 10 Aug compared to the untreated control. The application of calcium compounds did not reduce white mold severity compared to the untreated control. Yields were not significantly increased by the applications of calcium products.
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