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
POTATO WEED CONTROL
Richard Greenland
In this study we looked at different rates of Matrix and the timing of Matrix applications to potatoes.
Table 30. Herbicide treatments.
Table 32. Weed control ratings taken on September 24 and the yield data.
MATERIALS AND METHODS
| Soil: | Hecla sandy loam and Maddock sandy loam; pH=7.4; 2.2% organic matter; soil-P and soil-K were very high; soil-S was very low. |
| Previous crop: | 1996- oriental vegetables; 1995 - sweet corn; 1994 - cabbage, broccoli. |
| Seedbed preparation: | Disked on May 9. Multiweeded (field cultivated) on May 12. |
| Planting: | 'Russet Burbank' potato seed pieces were placed 1 ft apart in rows 3 ft apart on May 21. |
| Plots: | Plots were 20 ft long by 12 ft (four rows) wide. |
| 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 5 and fertigated 70 lbs N/acre on July 16 as 28-0-0. |
| Irrigation: | Overhead sprinkler irrigation as needed. |
| Pest control: | See Table 30 for weed control treatments. Dragged off on June 6. Hilled on June 24. Sprayed Imidan (1.3 and 0.8 lb/acre on June 26 and July 14), Provado (3.75 oz/acre on July 3), Pounce (8 and 6 oz/acre on July 9 and July 29), Asana (6 and 8 oz/acre on Aug 7 and Aug 20), and Ambush (6 oz/acre on July 22) for Colorado potato beetle control. Sprayed Manzate (2 lbs/acre on July 28), Bravo (1.5 pts/acre on July 21), and Dithane (1.5 qt/acre on Aug 7 and Aug 20) for early and late blight control. |
| Harvest: | Harvested on September 26. Yields, etc. were taken from a five-foot section of the middle two rows from each plot. |
RESULTS
None of the herbicide treatments injured the potatoes. All treatments controlled weeds better than the check treatment. There were no statistically significant differences between herbicide treatments in the control of any weed at the June 19 weed rating (see Table 31). However, there was a trend for poorer control of hairy nightshade for treatments that did not include two applications of Matrix or Matrix applied preemergence. This trend held true for the late weed rating and was statistically significant. Black nightshade control was poorer when no Dual plus Prowl was applied. Past experiments have shown that Matrix controls hairy nightshade but not black nightshade. The weed control treatments did not significantly affect potato yield or tuber size (see Table 32). Yields were numerically, but not statistically, higher with treatments vs. the check. The poor yield response to weed control was probably due to low weed pressure.
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Table 30. Herbicide treatments for the potato weed control study.
| Treatment Number | Herbicides | Rate (oz ai/acre) | Application timing |
|---|---|---|---|
| 1 | Matrix + Dual + Prowl + Matrix + Activator 90 |
0.25 + 24 + 10 + 0.25 + 0.25% v/v |
PRE POST2 |
| 2 | Matrix + Dual + Prowl + Matrix + Activator 90 |
0.375 + 24 + 10 + 0.125 + 0.25% v/v |
PRE POST2 |
| 3 | Matrix + Dual + Prowl + Matrix + Activator 90 |
0.375 + 24 + 10 + 0.25 + 0.25% v/v |
PRE POST2 |
| 4 | Matrix + Matrix + Activator 90 |
0.25 + 0.125 + 0.25% v/v |
POST1 POST2 |
| 5 | Matrix + Matrix + Activator 90 |
0.25 + 0.25 + 0.25% v/v |
POST1 POST2 |
| 6 | Matrix + Matrix + Activator 90 |
0.375 + 0.25 + 0.25% v/v |
POST1 POST2 |
| 7 | Dual + Prowl | 24 + 10 | PRE |
| 8 | Matrix +Dual + Prowl | 0.25 +24 + 10 | PRE |
| 9 | Matrix + Lexone + Activator 90 | 0.25 + 3 + 0.25% v/v | POST2 |
| 10 | Untreated |
PRE is just after last hilling; POST1 is when weeds in plots not receiving a PRE treatment are ½ to 1" tall. POST2 is when weeds in plots receiving a PRE treatment begin to break through that treatment. POST2 was also the time the canopy was beginning to close.
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Table 31. Early weed control in potatoes. Ratings taken on June 19.
| Treatment Number† | Hairy nightshade | Black nightshade | Redroot pigweed | Common lambsquarters | Yellow foxtail |
Common purslane |
|---|---|---|---|---|---|---|
| ------------------------------------------------ % control -------------------------------------------- | ||||||
| 1 | 100 | 100 | 100 | 100 | 100 | 100 |
| 2 | 100 | 100 | 100 | 98 | 100 | 100 |
| 3 | 98 | 100 | 100 | 98 | 100 | 100 |
| 4 | 95 | 83 | 100 | 100 | 100 | 100 |
| 5 | 95 | 93 | 100 | 90 | 100 | 98 |
| 6 | 100 | 95 | 100 | 98 | 98 | 100 |
| 7 | 90 | 100 | 100 | 95 | 95 | 100 |
| 8 | 98 | 100 | 100 | 100 | 100 | 98 |
| 9 | 90 | 93 | 98 | 98 | 98 | 100 |
| C.V. (%) | 6 | 8 | 2 | 7 | 2 | 4 |
†See Table 30 for treatments.
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Table 32. Weed control ratings taken on September 24 and the yield data for the potato weed control study.
| Treatment Number† | Hairy nightshade | Black nightshade | Redroot pigweed | Common lambsquarters | Yellow foxtail |
Yield | Tuber size |
|---|---|---|---|---|---|---|---|
| ---------------------------------- 0 to 10‡ ------------------------------ | cwt/acre | oz | |||||
| 1 | 9.8 | 10.0 | 10.0 | 9.8 | 10.0 | 267 | 7.2 |
| 2 | 9.3 | 10.0 | 10.0 | 9.5 | 10.0 | 314 | 7.5 |
| 3 | 9.5 | 9.5 | 10.0 | 9.8 | 10.0 | 285 | 7.2 |
| 4 | 8.8 | 9.3 | 9.8 | 8.3 | 10.0 | 326 | 8.3 |
| 5 | 8.3 | 10.0 | 10.0 | 8.0 | 9.8 | 400 | 7.7 |
| 6 | 9.3 | 9.3 | 10.0 | 9.0 | 10.0 | 338 | 9.0 |
| 7 | 7.0 | 10.0 | 10.0 | 8.5 | 9.8 | 263 | 7.1 |
| 8 | 9.5 | 10.0 | 10.0 | 9.5 | 10.0 | 438 | 8.6 |
| 9 | 7.3 | 9.8 | 10.0 | 9.3 | 9.3 | 331 | 8.6 |
| 10 | 4.5 | 9.8 | 5.0 | 6.0 | 7.3 | 203 | 7.2 |
| LSD (0.05) | 2.1 | NS | 1.0 | 1.8 | 0.8 | NS | NS |
| C.V.(%) | 17 | 5 | 7 | 14 | 6 | 34 | 15 |
†See Table 30 for treatments.
‡Rating are from 0 to 10, with 0 = plot completely covered
with weed, and 10 = no weeds in plot.
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Go to Oakes Irrigation Research Site Weed Control Studies page
Go to Oakes Irrigation Research Site 1997 annual report