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 CALCIUM COMPOUNDS
ALONE AND IN COMBINATION WITH BENLATE
FOR WHITE MOLD CONTROL IN DRY BEAN, 2000
Patrick L. Gross, Department of Plant Pathology, NDSU
A field trial was conducted at the Oakes Irrigation Research Site. 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 57 F. Sonalan + Dual II (2 qt/acre + 1.5 pt/acre) applied pre-emergence on 16 May, Raptor + COC (3 oz/acre + 2.5 pt/acre) applied post-emergence, cultivation, and handweeding provided good weed control. The plots were overhead sprinkler irrigated as needed. Calcium compound applications were made on 5 July (late bud) and 10 July (50 % bloom). Row closure was at 20% on 5 July and at 50% on 10 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 38 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 120F 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 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 17 July so a suspension of white mold spores was sprayed on the middle two rows of each plot. White mold was observed in the field five days later. White mold was uniform across the field.
Plants treated with two spray applications along with Benlate at 0.75 lb/acre significantly reduced white mold incidence compared to the untreated check on 3 Aug. Calcium sulfate + Benlate applied at 1 gal + 0.75 lb/acre with two sprays significantly reduced white mold severity compared to the untreated check on 3 Aug. Yields were significantly increased when two sprays were applied to plants except for calcium chloride and calcium sulfate applied alone.
Dry beans prices were low in 2000. It was difficult to make a profit on beans after fungicide costs were subtracted. Two treatments that produced the most profit per acre were calcium chloride and calcium sulfate when applied at bud stage and Benlate applied at 0.75 lb/acre 5 days later.
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Table 74. Incidence and severity of white mold in dry beans when using calcium compounds and Benlate. Oakes Irrigation Research Site, 2000.
| Chemicals | Rate/acre | No. of appli. | Incidence1 | Severity2 | Yield | ||
| Aug 3 | Aug 10 | Aug 3 | Aug 10 | ||||
| ------------------- % ------------------- | lbs/A | ||||||
| Check | --- | -- | 45 | 74 | 18 abc | 31 a | 2991 |
| Calcium Chloride3 | 1 gal | 2 | 49 | 73 | 18 ab | 30 abc | 3191 |
| Calcium Sulfate3 | 1 gal | 2 | 58 | 75 | 22 a | 36 a | 3226 |
| Calcium Chloride3+ Calcium Chloride + Benlate |
1 gal 1 gal + ¾ lb |
2 | 24 | 45 | 14 a-d | 27 abc | 3310 |
| Calcium Sulfate3 + Calcium Sulfate + Benlate |
1 gal 1 gal + ¾ lb |
2 | 34 | 53 | 13 bcd | 24 bcd | 3315 |
| Calcium Chloride4 + Benlate |
1 gal ¾ lb |
2 | 44 | 78 | 14 a-d | 33 ab | 3453 |
| Calcium Sulfate4+ Benlate |
1 gal ¾ lb |
2 | 45 | 63 | 17 abc | 28 abc | 3390 |
| Calcium Chloride + Benlate | 1 gal + ¾ lb | 2 | 10 | 26 | 9 cd | 16 e | 3500 |
| Calcium Sulfate + Benlate | 1 gal + ¾ lb | 2 | 13 | 39 | 8 d | 17 de | 3458 |
| Benlate | ¾ lb | 1 | 28 | 53 | 13 bcd | 21 cde | 3161 |
| Benlate | 1.5 lb | 2 | 11 | 29 | 15 a-d | 23 cde | 3636 |
| LSD (0.05) | 13 | 14 | 286 | ||||
1 Incidence based on number of infected plants divided by total number of observations.
2 Severity is based on means from diseased plants only. Means separated using the Duncan Test.
3 The first spray at late bud with calcium compound only and the second spray five days later.
4 Calcium compound applied only at late bud stage then Benlate only applied 5 days later.
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Go to Oakes Irrigation Research Site 2000 annual report
Go to Oakes Irrigation Research Site disease studies