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White Guinea yam is a tuber crop characterized by a long growth period over the entire rainy season, which is affected by changes in rainfall patterns owing to climate change. In this study, we investigated the effects of shifting the planting date of yam seed tubers on shoot growth and tuber development, which could be a plausible measure for adapting to changes in rainfall patterns. Our results revealed that tuber enlargement in plants with different planting dates started depending on the days after planting rather than the day of the year. This indicates that day length had little effect on tuberization. The final tuber yield was rarely affected by low rainfall during the early growth stage, whereas severe yield reduction occurred when the rainfall stopped during the tuberization period. We conclude that shifting the planting date backward to adjust for delayed rainy seasons increases the risk of severe yield reduction. [ABSTRACT FROM AUTHOR]

The selection of the sowing date is one of the most important decisions in soybean production. It is important for farmers to know the expected seed yield when developing a sowing plan. The objective of this study was to quantitatively reveal the decreased seed yield ratio during late sowing in southwestern Japan under irrigated conditions. Total above ground dry matter and distribution were measured from July to August sowing in 2018 and 2019 in Fukuyama, Hiroshima, Japan. The harvest index in the August sowing did not decrease compared to the July sowing under irrigated conditions. The decrease in yield was related to the total aboveground dry matter rather than to the harvest index. The decrease in total aboveground dry matter was related to the total amount of solar radiation intercepted rather than to radiation use efficiency. A significant regression equation was obtained for the relative yield, which was calculated from the maximum seed yield observed from early to mid-July. When seeds were sown after mid-July, our result showed that the seed yield will decrease by 0.60% per day for Sachiyutaka A1 and by 0.64% for Akimaro, even under conditions of 100% seedling establishment and controlled soil water conditions. This regression equation can be used in fields as an indicator of seed yield where irrigation is possible. [ABSTRACT FROM AUTHOR]

"Bouquet ears" is known to reduce grain yield in maize (Zea mays L.). The impact of agronomic factors on the bouquet occurrence rate (BOR) needs to be investigated. Two separate trials were conducted to assess the effects of nitrogen fertilizer, planting density, herbicide application, and planting date on the BOR in maize inbred lines (Mo17, K615/1, and KE72012/12) across two locations and 2 years (2018 and 2019). In Trial 1, the effects of nitrogen rate (200, 450, and 700 kg ha−1) and planting density (55,000, 70,000, and 85,000 plants ha−1) and in Trial 2, the effects of herbicide application (no-2,4-D application and 2,4-D at V5 and V7 stages) and planting date (May 25, June 4, and June 14) were evaluated. Planting density had no significant impact on the BOR in the inbred lines Mo17 and KE72012/12. In the inbred line K615/1, the BOR was inversely affected by planting density; BOR was 14% at 55,000 plants ha−1, 10% at 70,000 plants ha−1, and 8% at 85,000 plants ha−1. Delaying the planting date (PD) from May 25 till June 4 did not affect BOR; however, delaying PD to June 14 drastically increased BOR; KE72012/12 showed 3.56% BOR for June 14 PD, which was 215% higher than that for June 4 PD. Overall, the BOR could be significantly decreased in maize, provided proper genotypes are planted at suitable times (May 25 to June 4) at densities higher than 55,000 plants ha−1. [ABSTRACT FROM AUTHOR]

The DSSAT4.7-CERES model was employed to simulate plant-water nexus conditions in the future of Mazandaran province in Iran, using ensemble outputs of various GCMs and emission scenarios with LARS-WG 5.5 in the time period 2010–2100. The results showed during the 21st century, maize water requirement is expected to be reduced by 3.3–14.1%. Under climate change scenarios, both negative and positive changes in crop yield are projected, between −37.4 and 36.1%, which consequently results in a 5.1–27.2% reduction in water use efficiency (WUE) in the future periods. Deficit irrigation (DI) with 25% reduction in irrigation water depth (DI75) lead to a moderate reduction of 4.3–5.5% in WUE, but WUE was highly reduced under DI55. While early planting may reduce WUEs by 0.4–17%, late planting almost resulted in improved WUE, especially under DI75. Less frequent irrigation significantly reduces actual evapotranspiration, which consequently resulted in improved WUE by 0.57– 42.47%. In conclusion, the integrated assessment reveals that DI75, with an irrigation interval of 5 days, together with a 20 days delay in cropping date of maize in Mazandaran province, may be considered as an effective adaptation solution, when considering both food and water security. [ABSTRACT FROM AUTHOR]

Potato early blight disease, Alternaria solani and A. alternate, is of worldwide importance. It is necessary to take control measures, being economic, broadly applicable and well adapted by farmers. In this regard, for an integrated pest management programs, trails were conducted on irrigation types; sprinkler, drip and furrow systems, panting methods; one and two rows, delay in planting date, susceptibility of cultivars and application of fungicides impacts on early blight disease of potato. Descriptive statistics and principal component analysis were computed using SAS software version 9.1.3. (SAS Inc., Cary, NC) and the means comparison by Duncan multiple rang tests (DMRT). It was found that almost the entire relevant factors had significant impacts on reduction of the disease. Sprinkler and drip irrigations significantly decreased the disease in comparison with furrow irrigation system respectively. Double and single row planting reduced the disease effectively. A month and two weeks delay in planting date at various growth stages had a significant effect on disease reduction, respectively. Resistant and tolerant cultivars, Diamanté, Granola and Maradona cultivars had the lowest disease severity. Whereas, Marquis, Premier and Atlantic cultivars had the highest infection to early blight disease. Low-consumption fungicides, Flint (trifloxystrobin (ISO) belongs to the strobilurin) at the rates of 250, 200 and 150 g/ha were the most effective fungicide to control the potato early blight disease. This indicating that the combination of said cultural practices can effectively control the early blight disease of potato and also reduce fungicides consumption accordingly. [ABSTRACT FROM AUTHOR]

Sugarcane aphid, Melanaphis sacchari (Zehtner), recently emerged as a severe economic pest of sorghum in the USA. This insect was first discovered in the USA feeding on grain sorghum in Texas in 2013 and then rapidly spread across 19 additional states. In order to develop management practices to prevent yield loss, the objective of this study was to assess the value of host plant resistance and foliar applications of insecticide in five commercially available grain sorghum hybrids, across five locations in the southeastern USA. Field experiments were conducted in 2017 in Tift, Peach, and Pike Counties in Georgia; Barbour County in Alabama; and Darlington County in South Carolina. Foliar flupyradifurone applications were initiated at the action threshold of 50 aphids per leaf for each hybrid. Grain sorghum hybrids 'DKS48-07' and 'DKS37-07' showed resistance to M. sacchari across study locations. The most resistant variety, 'DKS48-07', required no foliar insecticide. Conversely, hybrids 'KS585' and 'DKS53-53' were highly susceptible. A single foliar application of flupyradifurone immediately suppressed M. sacchari populations and no further treatments were required. [ABSTRACT FROM AUTHOR]

Constraints are reported for the low productivity and quality of onion seed production in Ethiopia. Therefore, a field experiment was conducted at Kobo sub-center research station and Libso investment farm to study the influence of planting date and onion bulb size on yield and quality of onion seed. The experiment was laid out in Randomized Complete Block Design with three replications and involved three levels of onion bulb sizes and four levels of planting dates. The results of the study revealed that significant interactions between planting date and mother bulb size on seed yield ton ha-1, germination percentage, seed vigor index I and seed vigor index II. The highest seed yield (2.8 tons ha−1) was recorded from large onion bulbs of a size planted at Kobo early—October. Planted onion bulbs early-October increased seed yield (ton ha−1 by 21.7%) than planted early-November. Regarding onion bulb size, large bulbs increased seed yield (ton ha−1 by 40%) than the small bulbs. The highest (97.3) germination percentage was recorded from large onion bulbs planted at Kobo in early-October. Therefore, for the production of better yield and quality of onion seeds, early-October planting and large onion bulbs (4.1–5 cm) can be recommended in the study areas and other similar agro-ecology areas of the country. [ABSTRACT FROM AUTHOR]

The study parameterised and validated performance of AquaCrop model, to simulate attainable yields for chickpea crop in response to the effects of planting date in the Northestern Region of South Africa. Model calibration data were obtained from two field experiments of contrasting water regime, planted in 2014 winter season at University of Venda, South Africa, whilst data for model validation was obtained from 2015 planting season from the same station. The model performance was satisfactory, with a good combination between the simulated and observed canopy cover (CC), Soil water content (SWC), biomass (B) and grain yield (Y). All the statistical indicators (R2, RMSE, and MAPE) used to compare field observed and model-predicted parameters, showed good performance. For example, the regression analysis of simulated and observed yield showed a good relationship with R2 values of 0.949, 0.928 and 0.990 for early, normal and late planting dates, respectively, whilst RMSE was 0.135, 0.143 and 0.031 for early, normal and late planting dates. Similarly, SWC had strong regression relationship (R2 = 0.982, 0.949, 0.954, respectively, and a RMSE of 0.226, 0.696 and 0.310, respectively, in early, normal and late planting date). The results indicate that the model could be used for evaluating the effects of different planting dates on chickpea yield. [ABSTRACT FROM AUTHOR]

To move toward the principles of ecological agriculture in the direction investigating environmental and nutritional effects on yield and nitrogen efficiency of chickpea (Cicer arietinum L.), a field experiment was conducted on the experimental farm of Gonbad Kavous University, Iran; during the growing seasons of 2016 and 2017. The experimental layout was based on a factorial randomized complete block design with three replications and three factors. Three factors were Nitrogen (N) at four rates (0, 20, 40 and 60 kg N ha−1), two planting date (early January and early February) and two Mesorhizobium biological fertilizer levels (inoculation with Mesorhizobium and no-inoculation). Maximum seed yield, N agronomic efficiency, N utilization efficiency and N use efficiency were obtained from early January. The highest protein percent in seeds and N percent in straw were obtained from early February. Although, protein percent of seed, N percent of residues and seed yield increased with N rate, the N agronomic efficiency and N use efficiency decreased. The inoculation with Mesorhizobium had positive effects on yield and N use efficiency but had negative effect on N agronomic efficiency. The effect of biofertilizer levels was different at each planting date for seed protein percent in 2016. [ABSTRACT FROM AUTHOR]

Changes in oil and forage quality of maize due to agronomic practices have been poorly investigated. A field experiment was carried out to determine the effect of sowing date, and organic and inorganic fertilizers on fatty acid composition, physiological traits, yield, and yield components of maize in two cropping season. Sowing date (on time and delay planting), organic fertilizers (control, fresh farmyard manure, composted cattle manure, and vermincompost), and nitrogen (urea soil application, urea water application, and nitroxin treatment) were used for treatment group. Results showed second year performed better than first year. The interaction between planting time and organic fertilizer showed that the highest grain yield, oleic, and linoleic acid percentage was achieved in on-time planting and vermicompost treatment. In addition, the interaction effect of planting time and nitrogen showed that the highest oil yield and linoleic acid percentage was observed in on-time planting time and urea soil application. Although, palmitic and linolenic acid increased by delay planting date. In two years, soil application of urea yielded higher grain weight and oil yield than water application of urea and nitroxin. Results of this research demonstrated that application of organic fertilizers yielded to higher yield and yield componentsrather than first year. Also, by delaying planting time, the percentage of palmitic, and linolenic acid increased. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the effect of late planting on sucrose metabolism in cotton bolls and the relationship to fiber properties and within-boll yield components. Two cotton lines A201 and A705 were employed in a sowing date experiment where two temperature regimes during boll maturation period were created at mean daily temperature of 26.8°C, 28.3°C for early planting and 25.2°C, 23.1°C for late planting in 2016 and 2017, respectively. Boll size, seed mass per boll, seed index and fiber length were increased, and lint percentage was decreased by late planting. Greater cell wall invertase activity and the resultant hexose concentration in fibers were observed in late planting, and thus led to decreased osmotic potential accounting for the enhanced fiber length. Similarly, late planting increased the maximum of vacuolar invertase activity in ovules occurring at 5 days post anthesis (DPA) and hexose concentrations in embryos from 10 DPA afterwards which may favor embryo cell division, and thus increase final seed size. Our data indicate that acid invertase and hexose are implicated in the formation of within-boll yield components and fiber properties as affected by the lower temperature regime due to late planting. [ABSTRACT FROM AUTHOR]

The objective of this study is to validate the feasibility of a reflectance-based model for soybean crop area classification in advance of the county scale statistics from the United States Department of Agriculture (USDA). This classification method is named Reflectance-based North American Model (RNAM). It operates through the analysis of the main physically driven characteristics of farm fields and their specific radiometric profile obtained from Operational Land Imager (OLI) onboard Landsat 8. The state area of Illinois/US was selected because it is the largest soybean producer and accounted for nearly 35 percent of the total soybeans production in US. Farm fields within a set of 32 counties were analyzed for six crop years between 2013 to 2018. Results obtained from RNAM were compared to official estimates of USDA at county level. Coefficients R2 ranged between 0.92 and 0.96, indicating good agreement of the estimates. Results from RNAM were also validated with the geospatial reference map Cropland Data Layer (CDL) of soybeans from USDA. The overall map accuracy found was 93.86% with Kappa Index of Agreement of 0.795. Thus, RNAM was considered able to provide timely thematic soybean maps, in late September, in advance of the county scale statistics from USDA. [ABSTRACT FROM AUTHOR]

White yam (Dioscorea rotundata) is an important tuber crop of West Africa and the Caribbean, and one of the key limiting factors in its production is the availability of good quality planting material. The Adaptive Yam Minisett Technique (AYMT) was designed to help overcome this constraint. The paper presents an analysis of agronomic and economic data collected across four years (2013 to 2016) of AYMT plots planted in two areas within the middle-belt of Nigeria. Of the 136 plots that were established, 11% were lost to flooding and damage from Fulani cattle. Mean yield was 13.16 t/ha, 17,747 tubers/ha and the mean tuber weight was 0.73 kg. Plot yield declined with an increase in planting time, while plots owned by female farmers were on average planted later than those owned by their male counterparts; this helps explain the effect of gender noted in a previous study. Differences in yield were also noted between the two areas, which could also partly be explained by differences in planting time. The plots were profitable, with a mean cost over the four years of Naira 915,196/ha, revenue of Naira 3,197,786/ha and gross margin of Naira 2,282,591/ha (equivalent to US$4,039, US$14,319 and US$10,280 respectively). The main factor influencing costs and revenue was year, with no effect of gender. There is a need for more research on planting time in AYMT and how it interacts with factors, such as yam variety. [ABSTRACT FROM AUTHOR]

Below optimal temperatures can restrict growth of autumn planted tomato (Solanum lycopersicumL.), resulting in delayed fruiting and decreased fruit yield under field conditions. Technology for growing tomato under protected structures needs to be standardized. This study was conducted to determine effects of culture condition, planting date, and application of mulch on plant growth and fruit yield of tomato. To determine whether time of establishment affected results, plants were established in the first and third weeks of October and the first week of November of 2010 and 2011 in a polyhouse or open field using the mulch treatments black polyethylene, clear polyethylene, paddy straw, or no mulch. Root zone and air temperatures and net radiation were measured. Treatments affected plant height, fruit number, fruit weight, early yield, marketable yield, and total yield. Except for early yield, results were consistent between years. Black polyethylene mulch increased fruit number under the polyhouse and in the open field. Fruit weight was improved by mulch treatments only in the open field. Highest early, marketable, and total yields were from planting in the polyhouse in the third week of October using black polyethylene mulch, and this is attributed to increased root zone temperature, air temperature, and net radiation. Use of polyhouse and black plastic mulch combined with appropriate planting time improves early and total yields of tomato in areas where the production is constrained by suboptimal temperature conditions. [ABSTRACT FROM PUBLISHER]

Rice ratooning could be a practical way to increase rice production per unit area and per unit time. The objectives of this study were to evaluate variety [two inbreds (Cocodrie and Presidio) and three hybrids (Clearfield XL729, Clearfield XL745, and XL723)] and planting date (early and normal) effects on rice ratoon production in a sandy loam and clay soil at Eagle Lake and Beaumont, Texas, USA, respectively. A randomized design with four replications was used at both sites in 2008 and 2009 with a total of 160 observations. A PROC MIXED model was used to analyze the data with year and site as random factors and planting date and variety as fixed factors, and main crop (MC) and ratoon crop (RC) were analyzed using Repeated Measures analysis of variance (ANOVA). The grain yield of MC was only affected by the variety with hybrids having greater yields than inbreds (p < 0.01). However, both RC and total (MC plus RC) grain yields were affected by both planting date and variety (p < 0.01). For both RC and TC crops, early planting had greater (10%) grain yields than the normal planting (p < 0.01). Hybrids had 12% greater rain yields than inbreds (p < 0.001), but only for RC. The rice milling quality of MC was also affected by planting date and variety with greater milling yields with inbreds under normal planting. The results from this study indicate that rice ratoon and total crop yields could be improved through a combination of selected management practices including optimal variety selection and an earlier planting date. [ABSTRACT FROM AUTHOR]

In northwest India Japanese mint is being cultivated during spring season and faces both the extremes of temperature. The present investigation was planned to find out the optimum time of planting and harvesting with and without application of mulch to realize high quality essential oil. The experiment was laid out in split plot design keeping combinations of four date of planting (Jan 1, Jan 15, Jan 30 and Feb 15) and two straw mulch levels (No mulch and mulch @ 6 t/ha) in main plots and three harvesting schedules (120, 135 and 150 days after planting) in sub plots. Japanese mint planted on Feb 15 recorded maximum fresh herb, dry herb and oil yield, which were statistically at par with that planted on Jan 30 but were significantly higher than Jan 15 and Jan 1 plantings. Application of straw mulch resulted in significant improvement in fresh herb, dry herb and oil yield of Japanese mint. Fresh herb, dry herb and oil yield were significantly higher in crop harvested at 150 DAP than 135 and 120 DAP. Menthol content in mint oil did not influence with change in planting date or harvesting schedules while, menthone content decreased significantly with delay in harvesting from 120 to 150 DAP. A strong positive and linear relation was observed between emergence count and delay in planting of Japanese mint. Oil yield was positively correlated with plant height, stools count and fresh herbage production, while leaf to stem ratio has positive relation with oil content. [ABSTRACT FROM AUTHOR]

When Scots pine (Pinus sylvestris L.) seedlings are short-day (SD) treated in May or early June, height growth ceases but seedlings reflush within a few weeks and grow secondary needles (later referred to as early SD treatment). These “2-year-old-like” seedlings have been thought to be more stress tolerant than traditional 1-year-old pine seedlings, and thus suitable for summer and autumn plantings. To test this, seedlings sown in April were early SD treated over a 3-week period from the beginning of June and the seedlings were planted at 10-day intervals from the beginning of July until the end of September, and also during the following spring. Neither survival nor height growth of early SD-treated seedlings differed from untreated (1-year-old) seedlings. Moreover, for both early SD-treated seedlings and 1-year-old seedlings, those planted in summer grew and survived better after planting but had more multiple leaders than seedlings planted in autumn or spring. [ABSTRACT FROM AUTHOR]

We sought to establish the most effective combination of planting dates with insecticide spraying regimes for the management of insect pests of cowpea in the savannas of northeast Nigeria. The results after 3 sprays, made once each at the bud initiation, flowering, and podding stages, did not differ significantly from those after 2 sprays, made once each at flowering and podding, in terms of reducing insect pest population and increasing grain yield. Despite the reduction in insect infestation, delaying planting beyond mid-August reduced cowpea grain yield by 12.3%, on average. The yield of the medium-maturing variety IT89KD-391 was significantly higher when planted in mid-August and sprayed twice than when planted on the earlier or later dates. The yield of the indeterminate late-maturing variety ITKD89-288 was higher when planted in early August and sprayed thrice. Early- and medium-maturing cowpea varieties should therefore be planted in mid-August and sprayed twice. Late-maturing indeterminate varieties should be planted in early August and sprayed thrice. [ABSTRACT FROM AUTHOR]

Production during the off-season under tropical conditions can reduce yield and quality of lettuce (Lactuca sativa L.). The effects of shading with green nets and of mulching were examined for reduction of heat stress in the field. Irregardless of mulch type, the 15 Aug. planting had the lowest amount of bolting. For all cultivars planted on 15 Aug., irrespective of mulch, reduced head fresh weight and other vegetative components. The cvs. Robinson, Jordan, and Nader had the lowest leaf weights. Jordan and Wild Romaine cvs. of Romaine type lettuce were more susceptible to bolting and had higher values of fresh head weight because of high stem weight. It is recommended that summer cultivars be planted with black mulch on 15 Aug. Soil mulching, even at earlier planting dates, provided better conditions for summer cultivars to produce nonbolted heads of lettuce under shaded net structures. [ABSTRACT FROM AUTHOR]

Artemisia annua is an important crop grown for producing the anti-malarial drug artemisinin. It has been recently introduced to Bangalore's agro-climatic conditions of South India. A field experiment was carried out at the Central Institute of Medicinal and Aromatic Plants (CIMAP), Bangalore, from November 2004 to July 2007 to optimize the planting date for maximum herb, artemisinin and seed yield under the semi-arid tropical conditions of Bangalore. The study revealed that it was best to transplant seedlings of A. annua in the later part of October to get optimum herb, artemisinin and seed yield under Bangalore's agro-climatic conditions. [ABSTRACT FROM AUTHOR]

Information is lacking in soybean [Glycine max (L) Merr.] on whether or not variety selection and management practices can improve seed quality in early production systems. Effects of planting date, irrigation, genotype and maturity on seed quality traits in soybean were investigated in Arkansas for two years. Irrigation (I), planting dates (PD), and maturity groups/genotypes (MG/G) significantly affected seed quality traits. The MG/G, followed by I and PD treatments, made the largest contribution to variations in seed quality traits. Irrigation and late planting significantly improved seed standard and cold germination for most maturity groups. Irrigation also tended to increase seed protein content, whereas planting dates had no impact on seed protein and oil content. Both irrigation and planting dates had little or no effect on visual seed quality and seed pathogen infection. Maturity group and genotype significantly affected all seed quality traits. Late-maturing genotypes exhibited significantly higher standard and cold germination rate, fewer pathogen-infected seed, and better visual seed quality than early-maturing genotypes. Wide-row spacing improved seed germination. Seed germination and vigor of early-maturing genotypes decreased, whereas those of late-maturity genotypes improved when planting was delayed from April to June. Early-maturing genotypes were more responsive to irrigation when planted late. Significant correlation was found between cold and standard germination with other seed quality traits, including visual seed quality rating, disease-free seeds, and Phomopsis-infected seeds. We demonstrated that variety selection and irrigation were important in achieving high seed quality of early-maturing soybeans. [ABSTRACT FROM AUTHOR]

Soybean [Glycine max (L.) Merr.] growers in the mid- south United States have increasingly practiced early planting and double- cropping systems. Information on crop management is desired by soybean growers to improve production and profitability. Effects of irrigation and planting date on seed yield and other agronomic traits were investigated in soybean cultivars from eight maturity groups (MG) in 2002 and 2003 at two locations in Arkansas. The planting date (April, May, and June) and irrigation treatments significantly affected seed yield, plant height, and maturity. Significant effects were also observed for number of nodes, number of pods, and number of seeds per plant, whereas number of branches per plant was not affected by planting date and irrigation treatments. Irrigation improved seed yield by an average of 83% (986 kg/ha) in all experiments conducted across two years. Highest seed yield was achieved when soybeans were planted in May, followed by April and then by June planting. The MG V and VI cultivars, conventionally grown in Arkansas, produced higher seed yields than other maturity groups and were the most suitable cultivar selections when considering seed yield alone. Significant interactions were observed among planting date, irrigation, and maturity groups/genotypes. The MG IV was a better candidate for the double-cropping system (June-planting) because of its earlier maturity and high seed yield. For the early soybean production system (April-planting), MG I and II cultivars were potentially good selections because of their short growing periods and acceptable seed yields. The various planting dates and irrigation systems combined with proper cultivar selections provide soybean producers with more options for using the land and water efficiently. [ABSTRACT FROM AUTHOR]

Determination of different agronomical properties including soil-related parameters for enhanced canola (Brassica napus L.) production can be of great significance. Hence, the objectives were to determine the effects of different tillage systems, canola cultivars and different planting dates on: (i) canola yield and oil, and (ii) soil moisture and microbial carbon (C) and nitrogen (N). Two field experiments were planned as split-plot experiments in three replicates. The main plots were different tillage systems including no-tillage (NT), minimum tillage (MT) and conventional tillage (CT), and the subplots were the combination of different canola cultivars (PF and Hyola 401) and different planting dates (PD): 8 and 23 September and 7 October. Soil moisture under CT and PF was significantly less than that of MT and NT, and Hyola 401, respectively. Carbon and N microbial biomass was the highest at NT and on the first PD. The tillage method and planting date also significantly affected canola yield, oil content and the amount, and the number of earthworms. We may conclude that although the amount of yield was the highest at CT, it may be more agronomically sustainable to plant canola under NT or MT earlier during the autumn growing season. [ABSTRACT FROM AUTHOR]

Action thresholds as insecticide decision tools were developed and evaluated against chronic vegetative stage insect pests of irrigated transplanted rice in the Philippines: whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae( and two lepidopterous defoliators, Naranga aenescens Moore and Rivula atimeta (Swinhoe( (Lepidoptera: Noctuidae(. Through an iterative process, new threshold characters and insecticide technologies were evaluated at four sites (categorized as high and low pest density sites( over a 13-year period with the objectives of minimizing insecticide usage and maximizing farmer adoption. Characters were evaluated as to their ability to predict significant pest densities and yield loss. Significant differences occurred between high and low pest density sites among the best characters and monitoring methods for both pests. Earlier-planted fields were used as a forecasting tool, showing best results in the high pest density sites. Overall, most threshold characters performed well but the insecticide response was poor. Insecticide control was better with some threshold characters than others due to better timing. Seedling root soak with isofenphos was more effective than granules or foliar sprays against whorl maggot but required a decision before planting. Foliar sprays were most effective if applied twice (2 and 7 days after transplanting(. The best performing characters for whorl maggot were 1 – 2 eggs/hill for the low pest density sites and 15 – 30% damaged leaves in earlier planted fields in high density sites. The best performing characters for defoliators were 10% damaged leaves monitored in earlier planted fields for high density sites and 10% damaged leaves in low density sites. Carbaryl was the most effective insecticide spray against defoliators that combined performance and relative safety. [ABSTRACT FROM AUTHOR]

Action thresholds (ATs) as insecticide application decision tools were developed and tested against mainly yellow Scirpophaga incertulas (Walker) and white S. innotata (Walker) rice stemborers in four sites in the Philippines over 68 crops. Damage incidence was low with a mean over all crops and sites of 2% deadhearts (DH) and 3% whiteheads (WH) based on weekly sampling. Highest incidence reached 19% WH as a mean of one crop and 31% WH in an individual field in 1 week. AT characters were based on deadhearts, egg masses, or flushed moths. A mean of 9% fields exceeded ATs in the vegetative, 5% in the reproductive, and 4% in the ripening stages. The most effective AT character in each of the three growth stages was percentage DH with 5% being optimal in the vegetative, 25% in the reproductive, and 10% in the ripening stages. These ATs resulted in 96 – 99% correct decisions based on criteria involving DH and yield loss benchmarks set from earlier studies on economic loss. Insecticide response to the highly accurate ATs was a disappointing [ABSTRACT FROM AUTHOR]

Action thresholds (AT) as insecticide application decision tools were developed and tested against rice leaffolders Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae) in four sites and 68 crops over a 13-year period in the Philippines. Leaffolder damage levels were generally low with a mean over all sites and crops of 2 – 3% damaged leaves (DL) and 6 – 9% in a given site as a per-crop average based on weekly samplings, with highest incidence per field on a given sampling date of 48%DL. The damage incidence over a typical crop cycle formed a bell-shaped curve with maximum numbers in the late reproductive and early ripening stages. Continuous population buildup over the planting cycle did not occur in any one site over the season, thus a strategy of monitoring earlier planted fields to forewarn against impending economic damage had no basis. ATs were based on different levels of percentage DL, number of larvae per hill (L), and density of flushed moths. Collectively ATs were surpassed in 1, 12, and 4% of fields in each of the three main growth stages. A scoring system was based on benchmark criteria including both leaffolder damage and yield loss. The 15%DL threshold performed best in all growth stages, only equaled by 1L in the vegetative stage, scoring 93 – 99% correct decisions in each of the growth stages. Flushed moths produced the most false positive decisions and the lowest performance scores. The best insecticide response gave only a disappointing 53% control and therefore was a significant weakness in using AT technology. BPMC, endosulfan, and monocrotophos performed the best and azinphos-ethyl and Bt the least. Sites with the highest densities had the most rapid rise in damage levels, thus requiring more frequent monitoring. Low leaffolder damage levels were most likely due to the activity of natural enemies. Given the ability of high tillering varieties to compensate from pest damage, farmers would be better off embracing integrated crop management as a preventative measure to bolster inherent tolerance levels combined with crop monitoring based on historical population levels. In sites with a record of high damage levels, monitoring should start 4 weeks after transplanting (WT) on a weekly basis and more risk averse farmers may increase the interval to twice a week during flag leaf stage. In sites with lower observed levels, monitoring can begin 6 WT on a weekly basis and continue through the flag leaf stage. Significant yield increases were recorded with the best AT characters despite evidence of modern rices to tolerate high damage levels. Reasons for this apparent paradox are discussed. [ABSTRACT FROM AUTHOR]

Field performance of three weight classes of small minitubers ranging from 6.0 – 18.0 g was studied in two years at different planting dates. The heavy minitubers gave higher values than light minitubers for tuber yield, tuber weight, tuber number and stem number. Minitubers produced approximately 2 – 4 stems per plant. Approximately 9 – 19 t ha-1 tuber yields were obtained from minitubers averaged over minituber classes, cultivars and planting dates. The performance of minitubers varied between planting dates, minituber classes, years and potato cultivars. These results indicate that small minitubers can be used effectively to expand production of basic potato seed stocks. [ABSTRACT FROM AUTHOR]

High temperatures can cause abortion of flowers and fruit in tomato (Lycopersicon esculentum Mill.). Cultural activities might be used to counter effects of temperature. Topping of tomatoes to extend the harvest season of 4 cultivars with reported ability to set fruit under high temperatures, was tested over planting dates. Effects of topping and cultivars were significant, but their interaction was not. The highest yield was obtained from the early (November) transplanted crop, and topping of plants established in November or February was effective for some cultivars. A breeding line, 'CR-2-P8-5-1', was judged best for total as well as for late yield. [ABSTRACT FROM PUBLISHER]

Action thresholds as decision tools for insecticide application were developed and tested against the major insect pests of rice at four sites in the Philippines over a 13-year period. Action threshold treatments were compared to the farmers' practice, prophylactic insecticide usage, and an untreated check. Yield loss data using the insecticide check method partitioned yield losses over three crop growth stages in the same test fields. Chronic pests that exceeded action thresholds in 79% of fields were whorl maggot Hydrellia philippina Ferino (Diptera: Ephydridae), defoliators Naranga aenescens Moore and Rivula atimeta (Swinhoe) (Lepidoptera: Noctuidae), leaffolders Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae), and stemborers Scirpophaga incertulas (Walker) and S. innotata (Walker) (Lepidoptera: Pyralidae). Minor chronic pests reached threshold levels in only one site each: rice bug Leptocorisa oratorius (F.) (Koronadal), whitebacked planthopper Sogatella furcifera (Horvath) (Zaragoza) and green leafhopper Nephotettix virescens (Distant) (Guimba); brown planthopper Nilaparvata lugens (Stål) did not exceed a threshold in any field. Stemborers were the most important pest group in terms of yield loss. Despite the insecticide check method underestimating losses, a mean crop loss of 0.62 t/ha was measured which showed ample scope for corrective action. But loss was evenly distributed across crop growth stages (0.15?–?0.24 t/ha) reducing the impact of insecticides. Action threshold treatments overall outyielded the untreated check, more so in the two sites with highest pest density. The benefit of thresholds was to reduce insecticide usage, as a cost saving. However all the practices showed poor economic returns including the farmers' practice. Farmers' practice employed low insecticide dosages and timing was not consistent with pest damage, but yields were often similar to threshold treatments. Farmers appear to use insecticide more for risk aversion than for profit. The best threshold characters when evaluated against resulting pest density and yield loss criteria showed accuracies >?90% correct decisions. Future work is needed to improve the insecticide response rather than monitoring tools. Thresholds need to be incorporated into improved crop management, which was often found suboptimal by farmers, to take advantage of the high levels of tolerance in modern high tillering cultivars. Crop husbandry practices which improve yield potential such as selection of longer maturing varieties and nitrogen fertilizer may be a more effective pest management strategy than insecticides. [ABSTRACT FROM AUTHOR]

The extent of onion (Allium cepa L.) bulb and seed production varies with different production management practices. Field experiments were conducted during the 2000-2001 and 2001-2002 growing seasons to evaluate bolting and yield in onion grown with blue, red or white mulch in comparison to those grown with manual cultivation or chemical weed control treatment without mulch. The role of low temperature at the post-juvenile growth stage in bolting induction was also examined. Bolting was sometimes higher under mulch as compared to plots receiving manual hoeing or herbicide treatments. No particular mulch color appeared to consistently favor bolting. There was an inverse relationship between bolting and yield. Treatments did not affect germination of harvested seeds. Onion plants which were exposed to low temperature after attaining the critical growth stage for vernalization produced more inflorescences. [ABSTRACT FROM PUBLISHER]

There is little information on the types and frequencies of cultural practices in watermelon production that are commonly used. To better understand opportunities and pitfalls in watermelon production, and to provide direction for extension personnel, we undertook a survey of characteristics of watermelon production in Oklahoma. This survey included 102 fields and 1,260 ha in 22 counties-up to 30% of the estimated watermelon area in 1998 and 1999. Triploid cultivars, plastic mulch, beehives, raised beds, and 2-row planting was found in < 30% of fields. Transplants, windbreaks, hoeing, and irrigation were used in < 55% of fields. Cultivation, fertilization, and crop rotation occurred in > 85% of fields. Overall, <7; of growers used low management intensity of open-pollinated cultivars, direct seeding, no cultivation, and no fertilization. Only < 1% growers used high management intensity of diploid or triploid hybrid cultivars, plastic mulch, raised beds, pollination management, transplanting, and irrigation, in addition to cultivation, fertilization, and crop rotation. High intensity management was frequently used in the southwestern district, compared to the northeastern and southeastern districts. Given techniques available, management intensity could be increased in Oklahoma. [ABSTRACT FROM PUBLISHER]