Joel Felix

Effect of Weed Emergence Time and Intervals of Weed and Crop Competition on Potato Yield

A field study was conducted at Vezaiciai branch of the Lithuanian Institute of Agriculture from 1998 to 2000 to determine weed emergence dynamics in potato and to estimate the effect of different intervals of weed crop competition on potato tuber yield. Treatments varying in intervals of weed-free conditions and competition were laid out in a randomized complete block design with six replications. The greatest emergence of annual broadleaf weeds (62 to 86% of the season total) in the crop was observed in the period from potato planting until flowering. Emergence of winter annuals such as field violet and scentless mayweed was greatest in the period from the 20-cm potato plant height until harvesting. Competition was most detrimental to potato tuber yield in the periods from planting until flowering, from planting until 25 d after flowering, or for the entire growing season. Potato tuber yield decreased by 8.1, 8.4, and 6.4%, respectively, during these competition intervals compared to the weed-free treatment. The results indicated that the critical weed-free period, when weed competition was detrimental to yield, started from planting until 25 d after flowering if regular interrow cultivation was applied. Nomenclature: Field violet, Viola arvensis Mur VIOAR, scentless mayweed, Tripleurospermum perforatum (Merat) M.Lainz MATIN, Potato, Solanum tuberosum L. ‘Mirta’

Response of Five Vegetable Crops to Isoxaflutole Soil Residues

Field experiments were conducted in 2001 and 2002 at two sites in Ohio to characterize the effect of isoxaflutole herbicide applied the previous year to field corn on processing tomato, bell pepper, cabbage, snapbean, and cucumber. Isoxaflutole was applied preemergence to field corn in 2001 at 0, 53, 70, 105, and 210 g ai/ha. There were no rotational crop cultivar by herbicide rate interactions at either site. Generally, there was a higher level of visible injury on crops at the Fremont site. Isoxaflutole residues at either site did not affect processing tomato yield. Bell pepper yield was reduced 33% when rotated into 210 g ai/ha rate plots only at Fremont. Snapbean marketable yield was reduced by isoxaflutole carryover from 70 and 210 g ai/ha rates resulting in 0.39 and 0.0 t/ha at Fremont. Similarly, isoxaflutole soil residues from 105 and 210 g ai/ha resulted in 14 and 24% visible injury on cucumber but did not reduce marketable yield. Site differences in soil characteristics and precipitation in the application year may have contributed to observed differences in crop response. Nomenclature: Isoxaflutole; bell pepper, Capsicum annuum L. ‘Aristotle’ and ‘Paladin’; cabbage, Brassica oleraceae L. var. capitata ‘Red Dynasty’ and ‘Huron’; corn, Zea mays L. ‘Pioneer 34B29 LL’; cucumber, Cucumis sativus ‘Vlasset’ and ‘Dasher 2’; processing tomato, Lycopersicon esculentum Mill. ‘Peto 626’ and ‘Heinz 9437’; snapbean, Phaseolus vulgaris L. ‘Strike’ and ‘Hialeah’. Additional index words: Herbicide carryover, herbicide soil residues, rotational crops, vegetable crops. Abbreviations: ANOVA, analysis of variance; CEC, cation exchange capacity; DAE, days after emergence; PRE, preemergence; SOM, soil organic matter.

Local conditions, not regional gradients, drive demographic variation of giant ragweed (Ambrosia trifida) and common sunflower (Helianthus annuus) across northern U.S. maize belt.

Abstract Knowledge of environmental factors influencing demography of weed species will improve understanding of current and future weed invasions. The objective of this study was to quantify regional-scale variation in vital rates of giant ragweed and common sunflower . To accomplish this objective, a common field experiment was conducted across seven sites between 2006 and 2008 throughout the north central U.S. maize belt. Demographic parameters of both weed species were measured in intra- and interspecific competitive environments, and environmental data were collected within site-years. Site was the strongest predictor of belowground vital rates (summer and winter seed survival and seedling recruitment), indicating sensitivity to local abiotic conditions. However, biotic factors influenced aboveground vital rates (seedling survival and fecundity). Partial least squares regression (PLSR) indicated that demography of both species was most strongly influenced by thermal time and precipitation. The first PLSR components, both characterized by thermal time, explained 63.2% and 77.0% of variation in the demography of giant ragweed and common sunflower, respectively; the second PLSR components, both characterized by precipitation, explained 18.3% and 8.5% of variation, respectively. The influence of temperature and precipitation is important in understanding the population dynamics and potential distribution of these species in response to climate change. Nomenclature: Giant ragweed, Ambrosia trifida L. AMBTR; common sunflower, Helianthus annuus L. HELAN; maize, Zea mays L.; soybean, Glycine max (L.) Merr.

Potato Response to Simulated Glyphosate Drift

Abstract Field studies were conducted in 2008 in Ontario, OR and Paterson, WA to determine the effect of simulated glyphosate drift on ‘Ranger Russet’ potato, including visual injury, shikimic acid accumulation, and tuber yield. Glyphosate was applied at 8.5, 54, 107, 215, and 423 g ae ha−1; which corresponds to 0.01, 0.064, 0.126, 0.254, and 0.5 of the lowest recommended (846 g ha−1) single application dose for glyphosate-resistant corn and sugar beet. Glyphosate was applied when potato plants were at 10-cm height, stolon hooking, tuber initiation, or bulking stage. The greatest visual foliar injury was observed when glyphosate was applied at a dose of 54 g ha−1 or greater and potato plants were at the hooking stage. The lowest foliar injury was observed when glyphosate was applied to potato plants at the bulking stage. The I50 glyphosate dose at 42 d after treatment (DAT) was estimated to be 167 g ha−1 for potatoes sprayed at the hooking stage. The corresponding glyphosate dose to result in 50% injury for potatoes sprayed at tuber initiation, 10-cm height, and bulking stages were 129%, 338%, and 438%, respectively, greater than hooking stage. The U.S. No.1 potato yield was inversely related to vine injury and shikimic acid accumulation. Shikimic acid accumulation increased when glyphosate was applied at 107 g ha−1 or greater. U.S. No.1 potato yield was reduced by 46% and 84% relative to the untreated control (55 and 76 T/ha) when glyphosate was applied at 107 g ha−1 to plants in the hooking stage at Ontario and Paterson, respectively. Tuber yields at both sites were lowest when glyphosate was applied at hooking and tuber initiation stages. Nomenclature: Glyphosate; potato, Solanum tuberosum L. ‘Ranger Russet’, SOLTU.

Sensitivity of sweet corn (Zea mays L.) and potatoes (Solanum tuberosum L.) to cloransulam-methyl soil residues

Abstract Field experiments were conducted in 1999 and 2000 at three sites in Midwestern USA to characterize the sensitivity of sweet corn and potatoes to cloransulam-methyl soil residues the year following application to soybeans. Cloransulam-methyl was applied pre-emergence to soybeans in 1999 at 0, 1 X , 2 X , and 4 X the recommended rate. In 2000, there was a cultivar-by-herbicide interaction for sweet corn injury at some but not all sites. Generally, the sweet corn injury was apparent at 7 days after emergence (DAE) and peaked at 28 DAE. Sweet corn and potato injury was more severe at sites with coarse soil texture and low soil organic matter. There was evidence of differential tolerance by different potato varieties. Results suggest that cloransulam-methyl residue the year after application to soybean is high enough to injure most sweet corn and potato cultivars.

Evaluation of imazosulfuron for yellow nutsedge (Cyperus esculentus) and broadleaf weed control in potato.

Abstract Field studies were conducted in 2007 and 2008 near Nyssa, OR, and Pasco and Paterson, WA to evaluate yellow nutsedge and broadleaf weed control and potato tolerance to imazosulfuron. No injury symptoms from imazosulfuron were evident on potato at Nyssa, whereas in Washington, imazosulfuron caused some chlorosis of potato foliage ranging from 6 to 15% and < 4% at 6 and 15 d after POST application, respectively. Sequential applications of imazosulfuron controlled yellow nutsedge better than a single PRE application. Sequential applications of imazosulfuron or imazosulfuron in combination with s-metolachlor controlled yellow nutsedge > 92 and 89% at 21 and 42 d after POST applications, respectively. Imazosulfuron controlled ≥ 98% of common lambsquarters and 100% of pigweed species. Imazosulfuron provided season-long control of common mallow at Nyssa. However, imazosulfuron failed to control Russian thistle at Paterson, and only partially controlled hairy nightshade. Yield of U.S. no. 1 potato at Nyssa ranged from 44 to 54 T ha−1 and 42 to 52 T ha−1 for imazosulfuron PRE and imazosulfuron sequential treatments in 2007 and 2008, respectively. U.S. no. 1 potato yield following imazosulfuron PRE and sequential treatments at Pasco ranged from 49 to 57 T ha−1 in 2007, and at Paterson from 36 to 54 T ha−1 in 2008. Lower yields in 2008 were attributed to poor control of hairy nightshade. Imazosulfuron has potential to become a valuable tool for yellow nutsedge management in potato. Studies are needed to evaluate the soil persistence for imazosulfuron in order to determine safety to crops grown in rotation with potato. Nomenclature: Imazosulfuron; rimsulfuron; s-metolachlor; common lambsquarters, Chenopodium album L.; common mallow, Malva neglecta Wallr.; hairy nightshade, Solanum physalifolium Rusby; pigweed, Amaranthus spp.; Russian thistle Salsola tragus L.; yellow nutsedge, Cyperus esculentus L. CYPES; potato, Solanum tuberosum L. ‘Russet Burbank’ and ‘Shepody’.

Weed seedbank dynamics in post conservation reserve program land

Abstract The influence of tillage, crop rotation, and weed management regimes on the weed seedbank in land previously under the conservation reserve program (CRP) for 8 yr was determined from 1994 through 1997. The study was a split-plot design with four replications, two tillage systems, two crop rotations, and three weed management treatments. Eleven weed species were recorded in 1994 and 1995, and 13 in 1996 and 1997. The weed seedbank was dominated by broadleaf species. In 1994, the first year after CRP, the seed population density in the top 15 cm of the soil profile was 51,480 seeds m−2, of which 60 and 20% were pigweed and common lambsquarters. The population density of pigweed seeds in the seedbank increased over time and reached 51,670 seeds m−2 in 1996. In contrast, the seed population density for foxtail species was only 417 seeds m−2 in 1994, but it increased to 7,820 seeds m−2 in 1997. The large increase in foxtail species seed population density in the 4-yr period was mainly in the no-herbicide weed management treatment. The weed seedbank was reduced similarly by band and broadcast herbicide treatments. Tillage and crop rotation did not influence the weed seedbank or Shannons diversity index, nor did they interact with the weed management treatments in any of the years. The weed seedbank population density varied with the years and time of soil sampling. Weed seed population densities tended to be greater in the fall but declined significantly by time of the spring sampling. The no-herbicide treatment had a more diverse weed seedbank compared with band and broadcast herbicide weed management treatments. An average of one grass and three broadleaf weed species were identified in the three weed management treatments. Band and broadcast herbicide treatments reduced the weed seedbank population density but did not affect the number of broadleaf weed species observed. Nomenclature: Common lambsquarters; Chenopodium album L. CHEAL; foxtail species; Setaria spp.; pigweed species; Amaranthus spp.

Yellow Nutsedge Control and Reduced Tuber Production with S-metolachlor, Halosulfuron plus Dicamba, and Glyphosate in Furrow-Irrigated Corn

Abstract Yellow nutsedge is an important weed problem in furrow-irrigated fields in the Treasure Valley of eastern Oregon and southwestern Idaho. Field studies were conducted in 2008 and 2009 to evaluate the effect of PPI S-metolachlor or EPTC followed by POST halosulfuron and dicamba plus glyphosate or glyphosate alone on foliar yellow nutsedge control and tuber production in corn. Corn plant height at 8 and 24 d after treatment (DAT) was reduced 20 and 17%, respectively, in POST herbicides alone compared with PPI plus POST herbicide treatments. Yellow nutsedge control at 8 DAT averaged 78% for treatments that included PPI application of EPTC or S-metolachlor 1,600 g ai ha−1 followed by halosulfuron plus dicamba (35 plus 155 g ha−1 or 70 plus 310 g ha−1) plus glyphosate 785 g ha−1 compared with POST treatments alone (49%). The control at 24 DAT was 84% for treatments that contained halosulfuron plus dicamba compared with 73% for POST glyphosate alone. Yellow nutsedge tubers were reduced 56 to 68% among treatments at the end of 2008. Tuber reduction in 2009 was greater with treatments that included PPI herbicides followed by sequential halosulfuron plus dicamba (35 plus 155 g ha−1) plus glyphosate compared with glyphosate alone. Corn yield reflected the level of yellow nutsedge control and early-season weed interference. Treatments that included PPI herbicides had an average yield of 8.2 T ha−1 compared with 6.6 T ha−1 with sequential glyphosate alone. There was a correlation between percent foliar control and the number of yellow nutsedge tubers produced at the end of each year. Application of PPI herbicides followed by POST halosulfuron plus dicamba (35 plus 155 g ha−1 or 70 plus 155 g ha−1) plus glyphosate improved yellow nutsedge control, reduced early corn–weed competition, and produced the highest corn yield under furrow-irrigated conditions. Nomenclature: EPTC; dicamba; glyphosate; halosulfuron; S-metolachlor; yellow nutsedge, Cyperus esculentus L.; corn, Zea mays L., ‘DK C52-59-RR’.

Timing Potato Cultivation Using the WeedCast Model

Abstract A weed emergence prediction model, WeedCast, was used as a decision aid to schedule potato cultivation with and without herbicides at Wooster, OH, USA; Charlottetown, PE, Canada; and Fargo, ND, USA, from 2001 to 2003. Studies were laid out in a split-plot design with herbicides (±) forming the main plots and cultivation timing as subplots. Cultivation was done at 15, 30, or 60% of predicted weed emergence. Subplots were either left unsprayed or treated with metolachlor + metribuzin at 1.68 + 0.5 kg ai ha−1 and only cultivated at predetermined timing. Cultivation timing was based on predicted emergence of common lambsquarters at Wooster and Charlottetown, whereas eastern black nightshade was the indicator weed at Fargo. Weed control for the different cultivation timings varied among sites and years and was consistently better in plots where herbicides were followed by cultivation. Cultivation alone resulted in poor weed control and significantly reduced potato tuber yield compared with those in plots where weed control also included herbicides. Use of herbicides followed by cultivation and hilling increased tuber yield by 4.6, 4.3, and 8.7 t ha−1, when cultivations were done at 15, 30, and 60% of predicted weed emergence, respectively, and 12.2 t ha−1 for hilled-only plots. The average potato yield increase at Charlottetown was 9.7, 5.9, 6.9, and 7.4 t ha−1 for hilled-only plots and for hilled after cultivations at 15, 30, and 60% of predicted weed emergence with herbicides, respectively. There was no apparent pattern for treatment effects at Fargo, and the potato tuber yields were greatly reduced mainly because of excessive precipitation during potato establishment. Use of WeedCast as a decision-aid tool could be an asset in determining when to do the first and subsequent cultivations. It may work best for growers who use cultivations in potato to remove weeds that were not controlled by herbicides. Nomenclature: Metribuzin; common lambsquarters, Chenopodium album L. CHEAL; eastern black nightshade, Solanum ptycanthum L. SOLPT; potato, Solanum tuberosum L

Insect management and herbicide tolerance in near-isogenic sister lines of transgenic and non-transgenic sweet corn.

Abstract Pest management systems were evaluated in three near-isogenic lines of transgenic and non-transgenic sweet corn. The genetic transformation was reputed to confer resistance to corn earworm ( Helicoverpa zea ) and European corn borer ( Ostrinia nubilalis ), and increase tolerance to the herbicide glufosinate. Plots were planted with either a transgenic line or a non-transgenic sister line. Transgenic and non-transgenic varieties were treated with a herbicide; either glufosinate or bentazon, respectively, applied post-emergence. Ears of the non-transgenic varieties were protected by spraying insecticides every 3–4 days. Transgenic varieties were not sprayed. Glufosinate caused temporary chlorosis (5% or less) and stunting (6% or less) of transgenic sweet corn in one experiment. Bentazon did not injure non-transgenic varieties. Corn earworm and European corn borer control in transgenic sweet corn was superior to that achieved in non-transgenic varieties sprayed with insecticides. Damaged ears of transgenic varieties ranged from 0% to 6% and most damage was restricted to the tip of the silk end. A few small, moribund larvae were recovered. In contrast, 40% of non-transgenic varieties, on average, had damaged ears, despite regular spraying of insecticides. Ears of non-transgenic varieties were damaged more severely and many late-instar larvae were recovered.