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 BENLATE AND TOPSIN ON TIMING
FOR WHITE MOLD CONTROL IN DRY BEAN, 2000
Patrick Gross, Department of Plant Pathology, NDSU
Cooperator: Dupont
Table 75. Incidence and severity of white mold in dry beans when using Benlate and Topsin.
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 the each end of each row. Seeds were planted at a depth of 1.5" and an in-row spacing of approximately 2.5" using John Deere flexiplanters fitted with standard hoppers. The planter was set to plant 85,000 viable seeds/acre. At planting, soil moisture was high and soil temperature was 57 F. Herbicides, cultivation, and hand weeding provided good weed control. The plots were overhead sprinkler irrigated as needed. Fungicide applications were made on 7 July (10% bloom) and on 11 and 17 July. Row closure was at 30% on 7 July and at 80% on 17 July. Fungicide 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 from only 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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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 6 July. Canopy was starting to close the rows at the first spray application on 7 July.
White mold from natural inoculum was not observed in the field after the second spray application on 11 July. A suspension of white mold spores was sprayed on the middle two rows of each plot on 17 July to insure white mold infection. White mold was observed in the field five days later. White mold was uniform across the field. Plants treated with fungicides significantly reduced white mold incidence compared to the untreated check except Topsin applied at 10% bloom only. Plants treated with Benlate and Topsin treatments applied at 10% bloom and 10 days later significantly reduced white mold severity.
Yields were significantly increased by all treatments except Topsin applied at 10% bloom compared to the untreated check.
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Table 75. Incidence and severity of white mold in dry beans when using Benlate and Topsin. Oakes Irrigation Research Site , 2000.
| Chemical | Rate | Application timing | Incidence1 | Severity2 | Yield | ||
| Aug 3 | Aug 10 | Aug 3 | Aug 10 | ||||
---------------------- % -------------------- |
lbs/acre |
||||||
| Untreated Check | 45.0 | 73.8 | 17.5 | 31.0 a3 | 2991 | ||
| Benlate 50 WP | 1.5 lb | 10% bloom | 16.3 | 52.5 | 11.9 | 16.3 cd | 3391 |
| Topsin M 70 WSB | 1.5 lb | 10% bloom | 46.3 | 66.3 | 19.4 | 26.9 ab | 3075 |
| Benlate 50 WP | 1.5 lb | 10% bloom + 4 days | 11.3 | 28.8 | 15.3 | 22.7 bcd | 3636 |
| Topsin M 70 WSB | 1.5 lb | 10% bloom + 4 days | 21.3 | 50.0 | 14.3 | 23.9 abc | 3504 |
| Benlate 50 WP | 1.5 lb | 10% bloom + 10 days | 10.0 | 27.5 | 12.3 | 17.0 cd | 3573 |
| Topsin M 70 WSB | 1.5 lb | 10% bloom + 10 days | 10.0 | 28.8 | 10.6 | 14.7 d | 3592 |
| LSD (0.05) | 12.3 | 14.1 | ns | 286 | |||
1 Incidence based on number of infected plants divided by total number of observations.
2 Severity percentage is based only on diseased plants. Averaged over four replications.
3 Based on Duncan test. Values in this column followed by the same letter are not significantly different at the 0.05 level.
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Go to Oakes Irrigation Research Site 2000 annual report
Go to Oakes Irrigation Research Site disease studies