Estimated Yield Loss Research Articles

Perspectives on Potential Soybean Yield Losses from Weeds in North America

Weeds are one of the most significant, and controllable, threats to crop production in North America. Monetary losses because of reduced soybean yield and decreased quality because of weed interference, as well as costs of controlling weeds, have a significant economic impact on net returns to producers. Previous Weed Science Society of America (WSSA) Weed Loss Committee reports, as chaired by Chandler (1984) and Bridges (1992), provided snapshots of the comparative crop yield losses because of weeds across geographic regions and crops within these regions after the implementation of weed control tactics. This manuscript is a second report from the current WSSA Weed Loss Committee on crop yield losses because of weeds, specifically in soybean. Yield loss estimates were determined from comparative observations of soybean yields between the weedy control and plots with greater than 95% weed control in studies conducted from 2007 to 2013. Researchers from each US state and Canadian province provided at least three and up to ten individual comparisons for each year, which were then averaged within a year, and then averaged over the seven years. These percent yield loss values were used to determine total soybean yield loss in t ha−1and bu acre−1based on average soybean yields for each state or province as well as current commodity prices for a given year as summarized by USDA-NASS (2014) and Statistics Canada (2015). Averaged across 2007 to 2013, weed interference in soybean caused a 52.1% yield loss. Based on 2012 census data in the US and Canada soybean was grown on 30,798,512 and 1,679,203 hectares with production of 80 million and 5 million tonnes, respectively. Using an average soybean price across 2007 to 2013 of US $389.81 t−1($10.61 bu−1), farm gate value would be reduced by US $16.2 billion in the US and $1.0 billion in Canada annually if no weed management tactics were employed.

Use of remote sensing technology in the assessment of resistance of maize to tar spot complex

Assessment of Tar Spot Complex (TSC) severity in maize breeding experiments is conducted visually and may sometimes result in inconsistencies due to human interpretation. Disease scoring using remote sensing technologies may help bring more precision to the phenotyping process. An experiment for assessment of grain yield losses due to TSC was conducted at the Aguafria Experimental Station of the International Center for Wheat and Maize Improvement – CIMMYT in Mexico. Twenty-five maize genotypes were planted in spring of 2016 under a fungicide treatment to control TSC development and no fungicide treatment in a square lattice design with three replications. Four flights were carried out using an Unmanned Aerial Vehicle (UAV) equipped with a multispectral (550, 660, 735, 790 nm) and a thermal camera, simultaneously with the visual disease scorings and the yield was measured after harvesting. The preliminary results of the study indicated that the use of remote sensing in disease resistance phenotyping may be as effective as visual disease scoring since both correlate highly with the grain yield. Structural and chlorophyll vegetation indices (VIs) proved to be a good alternative for the estimation of yield losses caused by TSC in experimental field conditions, which may be potentially used for screening for resistance to this disease in maize genotypes, hypothetically reducing the need for visual disease scoring in the field.

Monitoring wheat fields by RapidScan: accuracy and limitations

Simple active radiometer sensors, such as RapidScan, enable agronomic decision-making and phenotyping within commercial wheat fields and experiments. The objectives of this study were: 1 - to evaluate the accuracy of quantitative biomass and nitrogen uptake estimation by the RapidScan, and 2 - to evaluate yield loss estimation based on NDVI. The RapidScan sensor was used as an assessment tool in the following studies: (i) over 3 years, 518 wheat samples were monitored during the vegetative growth period for biomass and aboveground nitrogen uptake and (ii) wheat cultivars were tested in an additional 4 field experiments, which were scanned weekly and correlated with grain yield. Results showed that accurate biomass estimation is limited up to about 100 g DM m−2. Grain yield, actual and potential, estimation is highly affected by the emergence date. The results showed that the use of a proximal-sensing technique allows for rapid and accurate crop monitoring and yield estimation, but emphasizing limitations in future use as well.

Potential Corn Yield Losses from Weeds in North America

Crop losses from weed interference have a significant effect on net returns for producers. Herein, potential corn yield loss because of weed interference across the primary corn-producing regions of the United States and Canada are documented. Yield-loss estimates were determined from comparative, quantitative observations of corn yields between nontreated and treatments providing greater than 95% weed control in studies conducted from 2007 to 2013. Researchers from each state and province provided data from replicated, small-plot studies from at least 3 and up to 10 individual comparisons per year, which were then averaged within a year, and then averaged over the seven years. The resulting percent yield-loss values were used to determine potential total corn yield loss in t ha−1 and bu acre−1 based on average corn yield for each state or province, as well as corn commodity price for each year as summarized by USDA-NASS (2014) and Statistics Canada (2015). Averaged across the seven years, weed interference in corn in the United States and Canada caused an average of 50% yield loss, which equates to a loss of 148 million tonnes of corn valued at over U.S.$26.7 billion annually.

Cereal stem borer management practices in subsistence farms of eastern Ethiopia

ABSTRACTIn eastern Ethiopia, empirical information regarding farmers’ perceptions and implementation of research results about stem borer management is either scarce or unavailable. A survey of 120 farmers from four maize- and sorghum-growing districts of eastern Ethiopia was carried out in 2014 to study common management practices of cereal stem borers. Drought, pests, and land shortage were reported as the main constraints to maize and sorghum production in the area. Stem borers were perceived as the most important pests in these crops. The estimated yield losses from stem borers ranged from 10% to 50%. The majority of the farmers reported not using chemical insecticides to control these pests due to lack of capital, unavailability, and lack of knowledge. Moreover, most farmers were not using improved maize varieties. Cultural practices were found to be the most promising control method of cereal stem borers. Despite differences among districts, farmers practiced crop rotation, intercropping, manipulation of planting dates, crop residue disposal, and post-harvest tillage as common control strategies, even though a considerable proportion of the farmers was not implementing these practices sufficiently. The design of appropriate strategies for stem borer management based on farmers’ needs and priorities should be promoted.

Early storage root bulking index and agronomic traits associated with early bulking in cassava

One of the attempts by farmers in counteracting the devastating effects of cassava brown streak disease (CBSD) on yield and quality of cassava is early harvesting. However, most varieties grown by farmers are often late bulking which increases the disease severity while on the other hand early harvesting results in significant yield losses. Farmers, therefore, need early storage root bulking cassava varieties in order to reduce the time to harvest leading to a faster rate of return to investment, while at the same time avoiding devastating effects of CBSD on yield and quality of cassava. The study was, therefore, conducted to identify high-yielding and early storage root bulking cassava genotypes as well as traits associated with early storage root bulking and estimate yield loss if any due to early harvesting. The overall aim was to generate information that would guide future improvement programmes for high-yielding and early-bulking cassava varieties in Malawi and other countries facing similar challenges. Trials were implemented using a square lattice design with three replications at two locations for two growing seasons with three harvest intervals (6, 9 and 12 months after planting, MAP). High yields were obtained of up to 9.5t/ha at 6 and 17.8t/ha at 9 MAP. Furthermore, the study revealed that yields obtained at 9 MAP were higher than those obtained at 12 MAP for some genotypes which suggests that such genotypes would be considered as early storage root bulking. Simple correlation analysis identified harvest index, storage root number, storage root diameter and storage root length as the selection criteria to achieve high fresh storage root yield (t/ha) and dry mass yield (t/ha). Path coefficient analysis allocated harvest index and shoot mass as the major selection criteria in improving fresh storage yield and dry mass yield. The study suggests that both source and sink capacities were important for determining early yield. Therefore, these two traits are the key determinants of early storage root bulking and should be used when selecting early-bulking cultivars and indirectly selecting for storage root number, storage root diameter and storage root length.

How much is a pheromone worth?

Pheromone-baited traps have been widely used in integrated pest management programs, but their economic value for growers has never been reported. We analyzed the economic benefits of long-term use of traps baited with the citrus fruit borer Gymnandrosoma aurantianum sex pheromone in Central-Southern Brazil. Our analysis show that from 2001 to 2013 citrus growers avoided accumulated pest losses of 132.7 million to 1.32 billion USD in gross revenues, considering potential crop losses in the range of 5 to 50%. The area analyzed, 56,600 to 79,100 hectares of citrus (20.4 to 29.4 million trees), corresponds to 9.7 to 13.5% of the total area planted with citrus in the state of São Paulo. The data show a benefit-to-cost ratio of US$ 2,655 to US$ 26,548 per dollar spent on research with estimated yield loss prevented in the range of 5-50%, respectively. This study demonstrates that, in addition to the priceless benefits for the environment, sex pheromones are invaluable tools for growers as their use for monitoring populations allows rational and reduced use of insecticides, a win-win situation.

How much is a pheromone worth?

Pheromone-baited traps have been widely used in integrated pest management programs, but their economic value for growers has never been reported. We analyzed the economic benefits of long-term use of traps baited with the citrus fruit borer Gymnandrosoma aurantianum sex pheromone in Central-Southern Brazil. Our analysis show that from 2001 to 2013 citrus growers avoided accumulated pest losses of 132.7 million to 1.32 billion USD in gross revenues, considering potential crop losses in the range of 5 to 50%. The area analyzed, 56,600 to 79,100 hectares of citrus (20.4 to 29.4 million trees), corresponds to 9.7 to 13.5% of the total area planted with citrus in the state of São Paulo. The data show a benefit-to-cost ratio of US$ 2,655 to US$ 26,548 per dollar spent on research with estimated yield loss prevented in the range of 5-50%, respectively. This study demonstrates that, in addition to the priceless benefits for the environment, sex pheromones are invaluable tools for growers as their use for monitoring populations allows rational and reduced use of insecticides, a win-win situation.

Economic estimates of feral swine damage and control in 11 US states

We report the results of one of the most comprehensive surveys on feral swine (Sus scrofa) damage and control in 11 US states (Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, Missouri, North Carolina, South Carolina and Texas). The survey was distributed by the USDA National Agricultural Statistical Service in the summer of 2015 to a sample of producers of corn (Zea mays), soybeans (Glycine max), wheat (Triticum), rice (Oryza sativa), peanuts (Arachis hypogaea), and sorghum (Sorghum bicolor) in the 11-state region. Producers that failed to respond to the initial mailing received multiple follow-up phone calls in an attempt to minimize non-response bias, and a total of 4377 responses were obtained. Findings indicate that damage can be substantial. The highest yield loss estimates occur in peanut and corn production in the Southeast and Texas. Control efforts are common, and producers incur considerable costs from shooting and trapping efforts. Extrapolating crop damage estimates to the state-level in 10 states with reportable damage yields an estimated crop loss of $190 million. Though large, this number likely represents only a small fraction of the total damage by feral swine in the 10 states because it only includes crop damage to six crops. We hope findings from this survey will help guide control efforts and research, as well as serve as a benchmark against which the effectiveness of future control efforts can be measured.

English

Cuscuta campestris (field dodder) is an obligate shoot parasite weed causing growth inhibition and yields losses of many agricultural crops worldwide. C. campestris is often observed in many crops; among is cassava in the eastern part of the Democratic Republic of Congo. In 2014, subsistence farmers realised that it may be responsible for yield reduction of many crops. This study evaluates the effect of C. campestris on the yield of a bio-fortified cassava. Six quadrats were installed in an existing 2 ha cassava field. In each quadrat, cassava plants infected by C. campestris were marked while in the same quadrat all other non-infected plants were controls. Yield parameters of 40 infected plants were compared to parameters from 43 uninfected plants. At the harvest time, the number of tubers by plant, fresh weight of tubers, tuber diameter, tuber length, and tuber dry weight were measured. Treatment means were separated using the least significant difference test at 5% probability level and the relative yield loss per cassava plant was estimated. Tuber diameter, tuber length and tuber dry weights were significantly reduced in C. campestris infested cassava as compared to controls (pV<0.001).  C. campestris caused substantial estimated yield losses of 48% per plant. The number of tubers was not reduced (pV=0.281), likely because C. campestris appeared six months after the planting date, when the tubers number was already set. Key words: Cuscuta campestris, cassava, yield, yield loss, field dodder, Democratic Republic of Congo.

Using SWAT Model to Determine Runoff, Sediment Yield and Nitrate Loss in Gorganrood Watershed, Iran

The adequacy of the SWAT model in the estimation of runoff, sediment yield and nitrate loss in the Gorganrood watershed was tested, using the existing spatial database as the primary data. The model was then executed for a 31-years’ time period. In combination with the SWAT model, the Sequential Uncertainty Fitting Program (SWAT-CUP and SUFI-2) was added used to calibrate and validate a hydrologic model of the watershed. The obtained values at 14 stations were between 0.48 to 0.83 for NS and 0.58 to 0.90 for R, respectively. The results showed that nitrate loss was higher in cultivated lands, and in the loess deposits. The maximum amounts of runoff and sediment yield were largely produced in steep areas of the watershed, where dry farming was practiced. In general, the results showed that SWAT could be a proper tool for simulating runoff, sediment yield and nitrate loss into the river.

Has the sensitivity of soybean cultivars to ozone pollution increased with time? An analysis of published dose-response data.

The rising trend in concentrations of ground-level ozone (O3 ) - a common air pollutant and phytotoxin - currently being experienced in some world regions represents a threat to agricultural yield. Soybean (Glycine max (L.) Merr.) is an O3 -sensitive crop species and is experiencing increasing global demand as a dietary protein source and constituent of livestock feed. In this study, we collate O3 exposure-yield data for 49 soybean cultivars, from 28 experimental studies published between 1982 and 2014, to produce an updated dose-response function for soybean. Different cultivars were seen to vary considerably in their sensitivity to O3 , with estimated yield loss due to O3 ranging from 13.3% for the least sensitive cultivar to 37.9% for the most sensitive, at a 7-h mean O3 concentration (M7) of 55ppb - a level frequently observed in regions of the USA, India and China in recent years. The year of cultivar release, country of data collection and type of O3 exposure used were all important explanatory variables in a multivariate regression model describing soybean yield response to O3 . The data show that the O3 sensitivity of soybean cultivars increased by an average of 32.5% between 1960 and 2000, suggesting that selective breeding strategies targeting high yield and high stomatal conductance may have inadvertently selected for greater O3 sensitivity over time. Higher sensitivity was observed in data from India and China compared to the USA, although it is difficult to determine whether this effect is the result of differential cultivar physiology, or related to local environmental factors such as co-occurring pollutants. Gaining further understanding of the underlying mechanisms that govern the sensitivity of soybean cultivars to O3 will be important in shaping future strategies for breeding O3 -tolerant cultivars.

Estimation of drought-related yield loss using the dynamic statistical model of crop productivity forecasting

The methodological approach is proposed to the estimation of drought-related crop yield loss based on the dynamic statistical model of crop productivity forecasting. The obtained results agree well with the total actual crop yield loss. The approach under consideration is the first stage of creation of operational assessment of expected loss.

Community-survey based assessment of the geographic distribution and impact of maize lethal necrosis (MLN) disease in Kenya

Maize Lethal Necrosis (MLN) is a viral maize disease that suddenly appeared in Kenya in the last few years and is causing major damages. Interventions are urgently needed, but information is lacking on its geographic distribution and losses caused. Group discussions were held in 2013 in 121 sublocations in the major maize zones, and respondents were asked if they had heard about MLN, when they first observed it, the proportion of households affected, and the estimated yield loss in affected areas. Responses were used to estimate the proportion of maize lost in the community, and these results were interpolated and combined with maize production data to estimate quantities lost. Western Kenya suffered most with more than half of farmers affected, followed by Central and Eastern Kenya, with up to a third of farmers. Yield losses in affected areas were highest in Western Kenya, followed by the highlands (in Central Kenya and the Rift Valley) and at the coast, but were low in the drylands (in Eastern Kenya). Total maize losses in Kenya were estimated at 0.5 million ton per year, or 22% of the average annual production before MLN, with a value estimated at $180 million. Losses were concentrated in Western Kenya, in particular the moist transitional zone (58% of all maize lost) and the moist mid-altitudes (19%), but also in the highlands (17%). Losses were small in the drylands and at the coast. Urgent action is needed to help farmers cope. In the short term, they need to be informed about the disease and provided with advice on appropriate agronomic practices. In the long term, varieties resistant to MLN need to be developed, first for the moist transitional and moist mid-altitude zones and followed by the highlands, but ultimately for all agroecological zones.

Estimation of yield losses in Brassica due to insect pests

An experiment was carried out to assess the yield losses due to insect pests in Brassica (B. juncea, B. rapa var. yellow sarson, B. rapa var. toria and B. rapa var. brown sarson) during winter of 2011–12, 2012–13 and 2013–14 at the Pulses and Oilseeds Research Station, Berhampore, Murshidabad, West Bengal. The study was conducted in two sets i.e., protected/sprayed and unprotected, in a randomized block design, with four replications. Data on the infestation and seed yield were recorded at weekly interval and at harvest, respectively. The loss in the seed yield due to mustard aphid (Lipaphis erysimi Kalt.) and sawfly (Athalia lugens proxima Klug.) infestation varied from 34.62 to 59.33%. The pooled data revealed that B. juncea (var. NRCDR-2) suffered less damage due to aphid (16.83 aphid/10 cm shoot of plant) and sawfly (6.48 larvae/10 plants) in the unprotected plots and thereby registered minimum seed yield losses of 34.62%. The overall findings confirmed the heavy losses to late sown brassica crops due to prolonged feeding of mustard aphid and sporadic attack of sawfly. Therefore, application of insecticides has been recommended in late sown rapeseed-mustard crop to reduce the attack of aphid.

Corn Yield Loss Estimates Due to Diseases in the United States and Ontario, Canada from 2012 to 2015

Annual decreases in corn yield caused by diseases were estimated by surveying members of the Corn Disease Working Group in 22 corn-producing states in the United States and in Ontario, Canada, from 2012 through 2015. Estimated loss from each disease varied greatly by state and year. In general, foliar diseases such as northern corn leaf blight, gray leaf spot, and Goss's wilt commonly caused the largest estimated yield loss in the northern United States and Ontario during non-drought years. Fusarium stalk rot and plant-parasitic nematodes caused the most estimated loss in the southern-most United States. The estimated mean economic loss due to yield loss by corn diseases in the United States and Ontario from 2012 to 2015 was $76.51 USD per acre. The cost of disease-mitigating strategies is another potential source of profit loss. Results from this survey will provide scientists, breeders, government, and educators with data to help inform and prioritize research, policy, and educational efforts in corn pathology and disease management. Accepted for publication 26 August 2016.

Mapping of Angular Leaf Spot Disease Hotspot Areas in Western Kenya Towards Its Management

Common bean (Phaseolus vulgaris L. ) is an important crop in the daily diet of more than 300 million people worldwide. Despite its importance, bean productivity is declining in western Kenya due to diseases and use of low yielding susceptible varieties. Among the diseases, ALS is a major biotic constraint of bean production in western Kenya. It causes an estimated yield loss of about 80% in the farmers’ field when severe. There is still limited information on pathogen distribution in western Kenya hindering breeding for ALS resistance. Therefore, a study was conducted to determine the occurrence of ALS disease in bean growing areas of western Kenya. A disease survey was carried out during the long and short rains seasons of 2013 in six agro-ecological zones namely: Low midland zone 1 (LM1) (Rongo and Bumula), low midland zone 2 (LM2) (Busia, Bungoma and Rangwe), low midland zone 3 (LM3) (Siaya and Teso north), low midland zone 4 (LM4) (Bondo), lower highlands (LH1) (Nandi Central) and upper midland zone 1 (UM1) (Sabatia and Nandi south). UM1 recorded the highest disease incidence and severity, whereas LM4 registered the least. Similarly, there was a significant positive correlation between disease incidence and severity (r = 0.711; p<0.0001). The study found the incidence and severity levels of ALS in western Kenya as high as 100% and 3 respectively. Therefore, farmers should be encouraged to use certified seeds to minimise the severity of the disease.

Yield loss and economic thresholds of yellow nutsedge in irrigated rice in function of cultivars

Weeds cause reduction in the rice yield. Little is known about the competitive ability of yellow nutsedge ( Cyperus esculentus ) with rice and the extent of the economic threshold (ET). The aim of this study was to determine the fit of the regression model to estimate hyperbolic yield losses and ET of yellow nutsedge in rice due to the cycle of cultivars (BRS Querencia - Early cycle and IRGA 424 - mid cycle). For this, a field study of competition in the agricultural year 2010/11 was conducted. Yield losses and ET of yellow nutsedge in rice crop is function on the competitive ability of rice cultivar used. The use of rice cultivar with early cycle, BRS Querencia, increases the ETs of weed in rice crops compared to the use of IRGA 424, mid-cycle. The hyperbola satisfactorily estimated yield losses that yellow nutsedge causes in rice crops. The explanatory variable, population of yellow nutsedge, was the best fitted to the model. Increases in yield, price paid for rice and control efficiency promoted by the herbicide and decreased cost of weed control, promote ET reduction in yellow nutsedge in rice crops, justifying the adoption of control measures of smaller populations of the weed.

A Survey of Feral Swine Damage in a Selection of U.S. States

We report the results of one of the most comprehensive surveys on feral swine damage and control in 11 U.S. states (Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, Missouri, North Carolina, South Carolina, and Texas). The survey was distributed by the USDA National Agricultural Statistical Service in the summer of 2015 to a sample of producers of corn, soybeans, wheat, rice, peanuts, and sorghum in the 11 states listed above. A total of 4,377 responses were obtained. Findings indicate that damage caused by feral swine can be substantial. The highest yield loss estimates occur in peanut and corn production in the Southeast U.S. and Texas. We hope findings from this survey will help guide control efforts and research, as well as serve as a benchmark against which the effectiveness of future control efforts can be measured.

The impacts of expansion and degradation on Australian cropping yields—An integrated historical perspective

Using a ‘stocks and flows’ model of Australian cropping we show that the expansion of aggregate cropping area has effectively masked landscape degradation impacts associated with continual production activity on “ageing” land. We estimate yield loss from combined land degradation to have increased to 9%, though the aggregate impact has effectively been masked by the introduction of new land. The model tracks the vintage of land since its first introduction to the agricultural system and calculates landscape degradation for four modes (dry-land salinity, irrigation salinity, acidification, and soil structure decline) according to historical production and ameliorating activities on each vintage. The model is calibrated with over 140years of varied historical data from the 1850s. Modelled farm-gate production volumes also incorporate technological factors, such as genetic and other yield increases. Despite the introduction of many technological advances in the cropping industry through the middle of the 20th century, production yields of Australian cereal grain remained relatively unchanged for decades. This can be explained by the rapid ageing and degradation of the cropping land due to a period of halted expansion. This perspective has important implications for future scenarios of the Australian cropping industry, which are unlikely to maintain land expansion at the long-term average of about 2%pa. Without major change, land degradation in our model results in yield loss of nearly 30% by 2060.