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Nader Soltani and George Lazarovits

Ammonium lignosulfonate (ALS) is a liquid waste by-product of pulp and paper industry that may be a source of organic fertilizer. Four plots each of tomato, pepper, broccoli, and corn were set up in a randomized block design on the AAFC-SCPFRC farm in the Spring 1998. Treatments were untreated control, 0.5% (v/w) ALS, and 1% (v/w) ALS. Soil samples were taken at 0, 2, 4, 8, and 22 weeks after amendment incorporation and analyzed for pH, microbial population, and water soluble ions. Soil temperature was measured at 8-cm depth. Leaf chlorophyll content was measured at four sampling dates. Tomato and pepper fruit were evaluated for symptoms of diseases. Soil temperature in 0.5% and 1.% ALS treatments were 2 and 7 °C warmer, respectively, than the control. Soil pH was lower in ALS-treated plots. 1% ALS caused more than 10-fold increase in bacterial population. Fungal populations in both 0.5% and 1% ALS treatments were 10- to 100-fold higher than control soil and continued to be higher to the last sampling date. Weeds were reduced by more than 50% by 0.5% or 1% ALS treatments. Both ALS rates caused an initial increase in NH4, NO3, NO2, K, Na, Cl, PO4, Ca, and SO4. NH4 and SO4 remained elevated for 22 weeks in both ALS treatments. ALS slightly increased chlorophyll content in tomato, pepper, and corn, but not in broccoli plants. The number of diseased tomato fruit in ALS plots were reduced by 50% to 70%. Bacterial spot decreased by more than 50% in both ALS-treated plots, while anthracnose declined by 50% to 75%. There were no significant differences in early and total yield of tomato, peppers, and corn. Early broccoli yield decreased in ALS treatments, while total yield increased over that of control in both ALS treatments.

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Darren E. Robinson, Kristen McNaughton and Nader Soltani

Pepper growers currently have limited access to many effective broadleaf herbicides. Field trials were conducted over a 3-year period in Ontario to study the effect of tank mixtures of sulfentrazone (100 or 200 g·ha−1 a.i.) with either s-metolachlor (1200 or 2400 g·ha−1 a.i.) or dimethenamid-p (750 or 1500 g·ha−1 a.i.) on transplanted bell pepper. Under weed-free conditions, there was no visual injury or reduction in plant height, fruit number, fruit size, or marketable yield of transplanted pepper with pretransplant applications of sulfentrazone applied in tank mixtures with s-metolachlor or dimethenamid-p. The tank mixture of sulfentrazone + s-metolachlor gave greater than 85% control of redroot pigweed (Amaranthus retroflexus) and eastern black nightshade (Solanum ptycanthum), but only 70% to 76% control of velvetleaf (Abutilon theophrasti), common ragweed (Ambrosia artemisiifolia), and common lambsquarters (Chenopodium album). The combination of sulfentrazone + dimethenamid-p provided good to excellent control of all weed species except velvetleaf. Based on this study, sulfentrazone and dimethenamid-p have potential for minor use registration in pepper.

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Nader Soltani, George Lazarovits and Arran Brown

Hungavit® products contain extracts of earthworm castings and are marketed by BioLife Ltd. as liquid Bio-leaf fertilizer and plant conditioner. Three experimental plots were set up on the AAFC-SCPFRC research farm to evaluate Hungavit®UR, Hungavit®P, and a preparation containing the equivalent amount of N, P, K fertilizer. In Spring 1998, four replicate plots/treatment of tomato, pepper, and potato were set up in a randomized block design. Each plot received the following treatments: untreated control, Hungavit®UR for tomato and pepper or Hungavit®P for potato, and the fertilizer equivalent of Hungavit®UR or P without the organic components. Tomato and pepper plants were treated three times by foliar application at the rate of 5 L/ha using 300 L of water/ha carrier. Leaf chlorophyll contents were measured at 2, 4, and 6 weeks after initial treatment application. Early and total yield were determined. Tomato fruit were evaluated for symptoms of bacterial spot, early blight, anthracnose, and blossom end rot; pepper fruit for bacterial spot; and potato tubers for potato scab. Both Hungavit® and its equivalent fertilizer application increased the chlorophyll readings significantly in at least one measurement for tomato, pepper, and potato plants. Although there were 40% to 55% fewer diseased tomato and pepper fruit in fertilizer and Hungavit® UR treatments, this was not statistically significant from the control treatments. Fertilizer treatment also reduced scab incidence in tubers by 50%, but the overall scab level was very low even in untreated plots. Hungavit® and its fertilizer equivalent had no significant effect on the early or total yield of tomato, pepper, or potato plants.

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Darren E. Robinson, Nader Soltani, Christy Shropshire and Peter H. Sikkema

There is little published information on the sensitivity of sweet corn to the PRE and POST application of isoxaflutole + cyprosulfamide. Four field trials were conducted during 2010 and 2011 in Ontario, Canada, to determine the sensitivity of ‘Merit’, ‘GH 4927’, ‘BSS 5362’, and ‘GG 741’ sweet corn hybrids to the PRE and POST application of isoxaflutole alone or in combination with cyprosulfamide. Isoxaflutole applied PRE or POST at 105 and 210 g a.i./ha caused as much as 12% visual injury, 18% reduction in height. and 24% reduction in marketable yield of some sweet corn hybrids evaluated. Isoxaflutole + cyprosulfamide applied PRE or POST at 105 and 210 g·ha−1 caused up to 7% initial injury in some sweet corn hybrids but the injury was transient with no effect on sweet corn height, cob size, and yield. Isoxaflutole applied POST was more injurious to sweet corn than when applied PRE; however, there was no differences in sweet corn injury between the PRE and POST applications of isoxaflutole + cyprosulfamide. Based on these results, there is potential for use of isoxaflutole + cyprosulfamide applied at 105 g a.i./ha in ‘Merit’, ‘GH 4927’, ‘BSS 5362’, and ‘GG 741’ sweet corn hybrids.

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Nader Soltani, Peter H. Sikkema and Darren E. Robinson

Limited information exists on sweet corn (Zea mays) tolerance to postemergence (POST) applications of thifensulfuron-methyl under Ontario growing conditions. Eight sweet corn hybrids were evaluated for tolerance to thifensulfuron-methyl in four field experiments conducted in 2003 and 2004. Thifensulfuron-methyl was applied POST at 6 and 12 g·ha–1 a.i., the registered and twice the registered rate for use in soybean in Ontario. Sweet corn hybrid responses to thifensulfuron-methyl varied. Delmonte 2038 was the most sensitive to thifensulfuron-methyl and had as much as 92% visual injury, 76% height reduction, and 98% yield reduction compared to the nontreated control. Empire, GH1861, GH2298, and GH2684 hybrids showed visual injury of 53%, 55%, 53%, and 61%, height reduction of 34%, 31%, 32%, and 26% and yield reduction of 77%, 68%, 68%, and 51%, respectively. GG214, GH2547, and GSS9299 sweet corn hybrids were not as sensitive to thifensulfuron-methyl. The initial sensitivity observed in these hybrids was minimal and transient with no effect on yield. Although thifensulfuron-methyl is safe for use on some sweet corn hybrids, it has the potential to cause severe crop injury and yield reduction in other hybrids and therefore it should not be recommended for weed management in sweet corn production in Ontario.

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Nader Soltani, Peter H. Sikkema and Darren E. Robinson

There is little information published on the effect of residues from postemergence (POST) applications of foramsulfuron and preemergence (PRE) applications of isoxaflutole, and isoxaflutole plus atrazine in the year after application on vegetable crops. Three trials were established from 2000 to 2002 in Ontario to determine the effects of residues of foramsulfuron, isoxaflutole, and isoxaflutole plus atrazine on cabbage, processing pea, potato, sugar beet, and tomato 1 year after application. Aside from a reduction in sugar beet plant stand, there were no visual injury symptoms in any crop at 7, 14, and 28 days after emergence (DAE) in any of the herbicide carryover treatments. Isoxaflutole residues reduced shoot dry weight and yield as much as 27% and 28% in cabbage, and 57% and 60% in sugar beets, respectively. The addition of atrazine to isoxaflutole caused further reductions in shoot dry weight and yield of cabbage and sugar beet. Isoxaflutole plus atrazine residues reduced shoot dry weight and yield as much as 42% and 43% in cabbage, and 58% and 82% in sugar beets, respectively. There were no adverse effects on shoot dry weight and yield of processing pea, potato, and tomato from isoxaflutole or isoxaflutole plus atrazine residues in the year following application. Foramsulfuron residues at either rate did not reduce shoot dry weight or yield of any crops 1 year after application. Based on these results, it is recommended that cabbage and sugar beet not be grown in the year following the PRE application of isoxaflutole or isoxaflutole plus atrazine.

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Nader Soltani, J. LaMar Anderson and Alvin R. Hamson

`Crimson Sweet' watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] plants were grown with various mulches and rowcovers and analyzed for relative growth rate (RGR), net assimilation rate (NAR), specific leaf area (SLA), leaf area index (LAI), and crop growth rate (CGR). Spunbonded polyester fabric (SB-PF) and perforated polyethylene film (PCP) rowcovers generally showed greater mean RGR, SLA and CGR than spunbonded polypropylene polyamide net (SB-PP), black plus clear combination plastic mulch and black plastic mulch alone. Plants on mulches and under rowcovers showed significant increases in RGR, NAR, and SLA over plants grown in bare soil. Carbon dioxide concentration inside the transplanting mulch holes was nearly twice the ambient CO, concentration. Growth analysis of sampled watermelon plants during early stages of development under various treatments was predictive of crop yield. Plants under SB-PF and PCP rowcovers produced the earliest fruit and the greatest total yield. An asymmetrical curvilinear model for watermelon growth and development based on cardinal temperatures was developed. The model uses hourly averaged temperatures to predict growth and phenological development of `Crimson Sweet' watermelon plants grown with and without rowcovers. Early vegetative growth correlated well with accumulated heat units. Results indicate a consistent heat unit requirement for the `Crimson Sweet' watermelon plants to reach first male flower, first female flower and first harvest in uncovered plants and plants under rowcovers. Greater variability was observed in predicting date of first harvest than first bloom.

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Sarah R. Sikkema, Nader Soltani, Peter H. Sikkema and Darren E. Robinson

Pyroxasulfone is an experimental herbicide for use in field corn (Zea mays L.) and soybean that may have potential for weed management in sweet corn. Tolerance of eight sweet corn hybrids to pyroxasulfone applied preemergence (PRE) at rates of 0, 209, and 418 g·ha−1 a.i. were studied at two Ontario locations in 2005 and 2006. Pyroxasulfone applied PRE at 209 and 418 g·ha−1 caused minimal (less than 3%) injury in Harvest Gold, GH2041, GH9589, GSS9299, GG214, GG446, GG763, and GG447 sweet corn hybrids at 7, 14, and 28 days after emergence. Pyroxasulfone applied PRE did not reduce plant height, cob size, or yield of any of the sweet corn hybrids tested in this study. Based on these results, pyroxasulfone applied PRE at the rates evaluated can be safely used for weed management in Harvest Gold, GH2041, GH9589, GSS9299, GG214, GG446, GG763, and GG447 sweet corn.

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Nader Soltani, Peter H. Sikkema, John Zandstra, John O'Sullivan and Darren E. Robinson

Topramezone is a newly introduced herbicide for use in field corn (Zea mays L.) that may have potential for weed management in sweet corn. Tolerance of eight sweet corn hybrids to topramezone applied postemergence (POST) at 0, 50, 75, 100, 150, and 300 g a.i. ha 1 were studied at one Ontario location in 2000 and two locations in 2001 and 2002. Topramezone applied POST at 50, 75, 100, and 150 g·ha 1 did not cause any visual injury in Calico Belle, CNS 710, Delmonte 2038, FTF 222, FTF 246, GH 2684, Reveille, and Rival sweet corn hybrids at 7 days after treatment (DAT) and caused minimal injury (less than 5%) at 300 g·ha 1 in all hybrids. The initial sensitivity observed in these hybrids was minimal and transient with no effect on visual injury at 14 and 28 DAT. Topramezone applied POST did not reduce plant height, cob size, or marketable yield of the sweet corn hybrids included in this study. Based on these results, topramezone applied POST at the rates evaluated can be safely applied to Calico Belle, CNS 710, Delmonte 2038, FTF 222, FTF 246, GH 2684, Reveille, and Rival sweet corn.

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Darren E. Robinson, Nader Soltani, Allan S. Hamill and Peter H. Sikkema

Combining herbicides and fungicides can improve production efficiency; however, there is little information on the effect of these mixtures on weed control and processing tomato crop response. Six field trials were conducted from 2002 to 2004 in Ontario to study the effect of rimsulfuron and thifensulfuron applied alone or in combination with metribuzin and with or without chlorothalonil or copper fungicides on processing tomato. There was no visual injury or reduction in marketable yield of processing tomato with rimsulfuron or thifensulfuron alone or when tank-mixed with chlorothalonil or copper hydroxide. Rimsulfuron, thifensulfuron, rimsulfuron plus metribuzin, and thifensulfuron plus metribuzin could be tank-mixed with chlorothalonil without a reduction in weed control. However, efficacy of rimsulfuron and thifensulfuron were reduced when tank-mixed with copper hydroxide. The reduction in weed control incited by adding copper hydroxide was overcome with a low rate (150 g·ha–1 a.i.) of metribuzin for thifensulfuron but not rimsulfuron. Application of rimsulfuron and thifensulfuron alone or with low rates of metribuzin and chlorothalonil could provide tomato growers with a single-pass treatment for the control of troublesome weeds and diseases.