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
TOMATO WEED CONTROL STUDY, 1997
Richard Greenland
Few herbicides are available for weed control in tomatoes. Hairy nightshade and black nightshade are the most difficult weeds to control in tomatoes. This study evaluated three standard herbicides (Treflan, Tillam, and Lexone) and two new herbicides (rimsulfuron and pyridate) for control of hairy and black nightshades. We also looked at pigweed, lambsquarters, and foxtail control.
Table 34. Early weed control and crop injury.
Table 35. Late weed control ratings.
MATERIALS AND METHODS
| Soil: | Embden sandy loam; pH=6.9; 3.0% organic matter; soil-P and soil-K were very high; soil-S was low. |
| Previous crop: | 1996 - oriental vegetables, spinach, lettuce, tomato; 1995- muskmelons, soybean; 1994 - edible bean. |
| Seedbed preparation: | Disked on May 9. Multiweeded (field cultivated) four times on June 11 to incorporate herbicides and to smooth seedbed. |
| Planting: | Tomatoes were seeded in the greenhouse on April 15. Plants were machine transplanted on June 13. Rows were spaced 8 feet apart. In-row spacing was 1 ft. As it was planted, each plant received one pint of fertilizer solution (1 gal 10-34-0 in 100 gal of water). Tomatoes were not staked. |
| Plots: | Plots were 17 ft long by 6 ft (one row) wide, with a 2-ft check strip between plots. |
| Fertilizer: | On April 23, broadcast 14 lbs N/acre and 70 lbs P2O5/acre as 10-50-0, 16 lbs N/acre and 19 lbs S/acre as 21-0-0-24, and 94 lbs K20/acre as 0-0-60. Sprayed 50 lbs N/acre on May 6 as 28-0-0 and fertigated 50 lbs N/acre as 28-0-0 through the drip system on July 23. |
| Irrigation: | Surface drip irrigation as needed. |
| Pest Control: | See Table 33 for weed control treatments. Sprayed Bravo (1.5 oz/acre on July 21and Aug 5) for blight control. Sprayed Asana (6 oz/acre on July 22, July 29, and Aug 5, and 8 oz/acre on Aug 21) for insect control. |
| Harvest: | Harvested date Sept 23 |
RESULTS
Treflan is a good basic herbicide but does not control hairy nightshade and is weak on several other weeds. Tillam suppressed hairy nightshade early in the season but the control did not last long. Tillam controlled foxtail. Lexone controlled pigweed, lambsquarters, and foxtail. Rimsulfuron controlled hairy nightshade, pigweed, lambsquarters, and foxtail but not black nightshade, which grew much more vigorously in plots sprayed with rimsulfuron than in other plots. The hairy nightshade competes with and suppresses black nightshade. When the hairy nightshade is selectively controlled, the black nightshade growth explodes. Pyridate was the only herbicide to effectively control black nightshade. It also controlled pigweed and lambsquarters. Pyridate stunted the tomato plants. It delayed tomato maturity when used only with a preplant incorporated herbicide. A combination of rimsulfuron and pyridate injured (stunted) tomatoes the most, but did not reduce tomato yield or delay tomato maturity. Rimsulfuron is not currently labeled for tomatoes. The wettable powder form of pyridate was labeled previously for tomatoes but may no longer be labeled.
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Table 33. Treatments for the Oakes Irrigation Research Station 1997 tomato weed control study.
| Trt. No. | Herbicide(s) | Rate (per acre) | Application timing† |
| 1 | Treflan | 1 pt | PPI |
| 2 | Tillam | 3 qts | PPI |
| 3 | Treflan + Lexone | 1 pt + ½ lb | PPI + POST1 |
| 4 | Tillam | 6 qts | PPI |
| 5 | Treflan + pyridate | 1 pt + 0.9 lbs | PPI + POST2 |
| 6 | Treflan + rimsulfuron | 1 pt + oz | PPI + POST1 |
| 7 | Treflan + rimsulfuron | 1 pt + ¾oz | PPI + POST1 |
| 8 | Treflan + rimsulfuron | 1 pt + oz | PPI + POST2 |
| 9 | Treflan + rimsulfuron | 1 pt + ¾ oz | PPI + POST2 |
| 10 | Treflan + Tillam + rimsulfuron | 1 pt + 3 qts + oz | PPI + POST2 |
| 11 | Treflan + rimsulfuron + pyridate | 1 pt + oz + 0.9 lbs | PPI + POST1 + POST3 |
| 12 | Treflan + rimsulfuron + rimsulfuron | 1 pt + oz + oz | PPI + POST1 + POST2 |
| 14 | Tillam + pyridate | 3 qts + 0.9 lbs | PPI + POST2 |
†Application timing:
PPI - June 11 (just before transplant)
POST1 - June 19 (right after transplant)
POST2 - July 9 (weeds 1 to 4" tall)
POST3 - July 15 (weeds 1 to 3" tall).
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Table 34. Early weed control and crop injury in the Oakes Irrigation Research Station 1997 tomato weed control study.
| Treatment Number† | Hairy nightshade | Black nightshade | Redroot pigweed | Common lambsquarters | Foxtail | Crop injury |
| ---------------------------------- weed control rating (1 to 100) ---------------------------- | ||||||
| 1 | 25 | 90 | 83 | 88 | 88 | 20 |
| 2 | 63 | 65 | 63 | 75 | 98 | 5 |
| 3 | 53 | 73 | 98 | 98 | 100 | 5 |
| 4 | 60 | 55 | 80 | 80 | 93 | 0 |
| 5 | 85 | 85 | 90 | 98 | 85 | 3 |
| 6 | 80 | 40 | 100 | 80 | 98 | 3 |
| 7 | 95 | 40 | 100 | 93 | 100 | 0 |
| 8 | 98 | 40 | 100 | 95 | 100 | 0 |
| 9 | 98 | 58 | 100 | 95 | 100 | 5 |
| 10 | 100 | 45 | 100 | 100 | 100 | 3 |
| 11 | 95 | 83 | 100 | 93 | 95 | 18 |
| 12 | 100 | 43 | 100 | 100 | 100 | 0 |
| 14 | 98 | 75 | 88 | 88 | 85 | 5 |
| LSD (0.05) | 18 | 21 | 9 | 10 | 8 | 11 |
| C.V. (%) | 16 | 24 | 7 | 8 | 6 | 153 |
†See Table 33 for explanation of treatments.
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Table 35. Late weed control ratings in the Oakes Irrigation Research Station 1997 tomato weed control study.
| Treatment Number† | Hairy nightshade | Black nightshade | Redroot pigweed | Common lambsquarters | Foxtail |
| ------------------------------ weed control rating (1 to 100) ------------------------ | |||||
| 1 | 13 | 80 | 85 | 88 | 90 |
| 2 | 23 | 73 | 70 | 73 | 95 |
| 3 | 33 | 73 | 95 | 98 | 98 |
| 4 | 38 | 68 | 78 | 73 | 95 |
| 5 | 78 | 93 | 90 | 95 | 90 |
| 6 | 60 | 53 | 98 | 80 | 98 |
| 7 | 90 | 30 | 100 | 90 | 100 |
| 8 | 95 | 38 | 98 | 93 | 100 |
| 9 | 85 | 55 | 98 | 88 | 100 |
| 10 | 100 | 40 | 100 | 98 | 100 |
| 11 | 85 | 78 | 100 | 93 | 83 |
| 12 | 95 | 40 | 100 | 100 | 100 |
| 14 | 85 | 75 | 85 | 85 | 73 |
| LSD (0.05) | 22 | 22 | 12 | 14 | 10 |
| C.V. (%) | 22 | 25 | 9 | 11 | 8 |
†See Table 33 for explanation of treatments.
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Table 36. Tomato yields in the Oakes Irrigation Research Station 1997 tomato weed control study.
| Treatment number† | Overripe | Red | Mature green | Total |
| ---------------------------------- tons per acre -------------------------------- | ||||
| 1 | 1.4 | 6.3 | 10.1 | 17.8 |
| 2 | 2.0 | 6.2 | 10.5 | 18.7 |
| 3 | 2.5 | 10.1 | 17.5 | 30.1 |
| 4 | 1.8 | 4.9 | 14.8 | 21.6 |
| 5 | 0.8 | 1.7 | 27.9 | 30.3 |
| 6 | 1.8 | 7.3 | 14.0 | 23.1 |
| 7 | 2.0 | 6.8 | 15.7 | 24.5 |
| 8 | 2.6 | 8.1 | 19.1 | 29.8 |
| 9 | 2.8 | 9.7 | 21.9 | 34.4 |
| 10 | 2.4 | 9.0 | 20.5 | 31.9 |
| 11 | 1.5 | 9.0 | 23.7 | 34.2 |
| 12 | 2.5 | 8.2 | 17.4 | 28.1 |
| 14 | 0.9 | 1.6 | 28.3 | 30.8 |
| LSD (0.05) | 1.1 | 3.2 | 6.6 | 8.5 |
| C.V. (%) | 42 | 33 | 25 | 22 |
†See Table 33 for explanation of treatments.
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Go to Oakes Irrigation Research Site weed control studies page
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