Worldwide, crop losses to weed infestations cost growers more than $100 billion, according to weed researchers. Research by the University of Illinois estimates yield losses due to particularly troublesome weeds such as waterhemp (Amaranthus) in soybeans at up to 40%. When another known resistant weed, Palmer amaranth (Amaranthus palmeri), is present, this figure can climb to as high as 79%.
With fewer new modes of action in the pipeline, more resistance issues are sure to arise in the future, said André Schreuder, managing director at Villa Crop Protection in South Africa.
In a world-first case of herbicide resistance, researchers confirmed in April that sowthistle (Sonchus) weed in the southeast of South Australia is resistant to 2,4-D, according to a report by ABC Rural News in Australia.
Dr. Ian Heap, director of the International Survey of Herbicide-Resistant Weeds, told FCI, “The case of 2,4-D-resistant sowthistle is concerning for those that would now rely on synthetic auxin-resistant crops in the USA.” The weeds that are most likely to evolve synthetic auxin resistance in these new crops are Kochia (Bassia scoparia), which has already been found to have glyphosate and dicamba resistance, tall waterhemp (Amaranthus tuberculatus), Palmer amaranth, horseweed (Conyza) and lambsquarters (Chenopodium), Heap said. A dicamba-resistant population of lambsquarters has been found in New Zealand.
For the QoI-class fungicides, including azoxystrobin, resistance is reported to be widespread but stable. These fungicides are valuable themselves to manage potential resistance problems in other modes of action such as the triazoles, dicarboximides and SDHI fungicides, said Dr. Andy Leadbeater, Syngenta’s head of Global Fungicides Product Biology, and chair of CropLife’s Fungicide Resistance Action Committee. Leadbeater told FCI the situation needs continued careful attention in the more “at risk for resistance” situations such as cereal Septoria (Europe, North America), grape powdery mildew and downy mildew (Europe, Americas, Asia), vegetable powdery and downy mildews (worldwide) and certain leaf spot diseases such as apple scab (worldwide), frogeye leafspot in soybeans (USA) or Alternaria in various crops (worldwide).
Schreuder points out a different challenge: the shift in focus from adherence to MRL levels to not having more than three to four residues total. “This makes it more difficult to market ready-mix compounds as part of a resistance management strategy, given the emphasis on the number of residues,” he says.
Can bio-based pesticides really help feed an ever-growing population? Or put in a different way, can agrochemicals alone help feed an ever-growing population? Says Ziv Tirosh, CEO of The Stockton Group, “The answer is clear and it is no. Agrochemicals have been massively used in years past and a growing number of them are struggling with resistance issues. In addition, the ‘ever-growing population’ is demanding ‘cleaner’ food with less chemical residues.” Tirosh says the company’s Timorex Gold is already replacing up to 25% of fungicide spraying programs, with the amount of crops it’s effective in treating and the number of geographies increasing. “We strongly believe that with continued research and development, the presence of biopesticides within spraying programs will only grow,” he says.
In developing countries where population growth is greatest, rich and poor farmers alike share the landscape and the challenges it brings. Regardless of input intensity, imbalances in water availability, soil fertility and seed availability conspire to create pockets of stress that regularly challenge the skills and resources of farmers in most countries, says Dr. Brian McSpadden Gardener of Ohio State University’s Department of Plant Pathology. Furthermore, infrastructure supporting agricultural production often falls short. Against this backdrop, biocontrols offer relatively low-cost, easy-to-manage and sustainable options for pest and disease control that can substantially increase productivity. Gardener points to successes in Africa with Beauvaria bassinia and atoxigenic strains of Aspergillus as key examples of how biocontrol programs can make meaningful differences in growers’ lives and incomes.
While chemical pesticides and biotechnologies offer substantial control and convenience, they come with costs that can be profitably offset by an integrated pest management program that includes biopesticides and biocontrols, says Gardener. “This creates a win-win-win, where the grower, consumer and the natural environment all benefit,” he says. “In greenhouses and field farming, biological approaches can complement resistance breeding, sustainable cropping strategies and outreach training efforts to help ensure success wherever access to chemical inputs and GMOs are constrained by economics, choice or consumer demand.”
Regulatory issues are one bump in the road alongside resistance and falling commodity prices, which have hit glyphosate prices hard in the past year. However, according to the Chinese Crop Protection Association (CCPIA), the price of glyphosate tech reversed its decline in March with a jump to $890 per tonne. March is when North American demand typically bumps up the domestic glyphosate price, but, said CCPIA, “insiders consider that in the long run, market demand has been increasing. With Monsanto’s new seed products launching into market, GM crops will be driven up, especially in Brazil (with the expansion of Intacta RR2 Pro soybeans), which will trigger a new trend of increased glyphosate demand.”
Scrutiny of the world’s biggest-selling herbicide is increasing following the World Health Organization research arm’s decision in March to classify it as a “probable carcinogen.” U.S. Environmental Protection Agency will soon require a weed resistance management plan for glyphosate similar to that placed on Dow AgroSciences’ Enlist Duo, according to Reuters.
Carissa Cyran, EPA spokesman, did not confirm details of the plan described in the Reuters report, but said that EPA will address the report by WHO’s International Agency for Research on Cancer in detail in July, at the same time it releases its preliminary human health risk assessment for glyphosate as part of its reevaluation program. Cyran noted, “In 2014, EPA reviewed over 55 epidemiological studies conducted on the possible cancer and non-cancer effects of glyphosate. Our review concluded that this body of research does not provide evidence to show that glyphosate causes cancer, and it does not warrant any change in EPA’s cancer classification for glyphosate.”
As fast as imidacloprid’s alleged role in pollinator health began grabbing headlines, Bayer CropScience constructed a 6,000-square-foot state-of-the-art North American Bee Care Center in Research Triangle Park, North Carolina and three Bee Care Technology Stations in the U.S. and Canada. The company kicked off its Feed a Bee campaign in early 2015 with the goal of growing 50 million flowers planted by the public by the end of the year. But the site was so heavily trafficked it took only three weeks to capture requests for 35 million seeds.
“It has blown our expectations out of the water,” says Jeff Donald, Bayer spokesman. “Clearly, the public is interested in bee health so we’re very excited by that.”
As the hot-button neonicotinoid issue gains visibility, a good deal of favorable evidence is emerging. USDA announced that honey bee hive numbers rose 4% last year on top of increases in the previous two years. Then, scientists at the University of Maryland, USDA and EPA released results in March of their four-year study, which found that imidacloprid does not significantly harm honey bee levels at real-world dosage levels.
To see significant negative effects, including a sharp decrease in winter survival rates, the researchers had to expose honey bee colonies to at least four times as much imidacloprid encountered under normal circumstances. Dr. Galen Dively, the study’s lead author, told FCI that given the dosage levels, “we were surprised we were not getting more effects.” Only at 20 times the normal exposure levels did the colonies experience more
EPA said in April it is unlikely to approve new neonicotinoid uses until new bee data have been submitted and pollinator risk assessments are complete. However, Dively believes that further restrictions will primarily affect homeowner uses. “For row crops, neonicotinoids are far better in terms of their toxicity profile to mammals than the organophosphates they replaced, which are orders of magnitude more toxic to people, and more leachable,” he said.
The European Union is another story. The bloc’s now two-year neonicotinoid ban is currently under review. The European Food Safety Authority watchdog will review data to contribute to conclusions on an updated risk assessment. In addition, the European Commission is working on an impact assessment to evaluate the socioeconomic consequences of the ban, says Jean-Charles Bocquet, director general of the European Crop Protection Agency.
5. Climate Change
Demand for new crop varieties with better resilience to stresses such as heat, drought, pests and diseases is likely to increase. But finding new genetic traits that can facilitate adaptation – and incorporating them into commercially successful varieties – is time-consuming, expensive and technically difficult. A new report by USDA’s Economic Research Service says that in recent years, demand for crop genetic resources from the U.S. National Plant Germplasm System (NPGS) has surged, even as the NPGS budget has fallen in real dollars.
“Because of insufficient private incentives, public-sector investment in the use of genetic resources will help determine the agricultural sector’s ability to maintain crop productivity,” the study’s authors Paul Heisey and Kelly Day Rubenstein stated. However, factors such as intellectual property rules for genetic resources and for research tools, or international agreements governing genetic resource exchange, have the potential both to promote and hold back more use of genetic resources for climate change adaptation.
Two kinds of technical change could reduce the costs of using genetic resources and thus increase their use for climate-change adaptation, the authors say: 1. Improvements in genetic resource collection, conservation, characterization and evaluation methods, and2. Increased efficiency in incorporating valuable genetic traits into commercial crop varieties.
Some headway is already being made. There is increasing uptake of the first drought-tolerant maize, Monsanto’s DroughtGuard, which was planted on 500,000 acres by more than 8,000 farmers in 2014, just two years after its launch. The same event was donated to the public-private partnership, Water Efficient Maize for Africa aimed at delivering biotech drought-tolerant maize to selected countries in Africa by 2017. China also granted full import approval for the trait in 2013.
“We’ve seen an overall increase in yield, and they outperformed leading products that we’ve had in the past,” said Justin Koehler, a farmer from McClean, Nebraska. “Planting DroughtGard Hybrids corn gives us the ability to perform the best, even in unfavorable conditions, which puts money in our pocket.”
Agriculture is also being targeted to take action on climate change from within. In April, U.S. Agriculture Secretary Tom Vilsack introduced a set of voluntary, incentive-based initiatives aimed at farmers and ranchers (among others) to help them reduce greenhouse gas emissions, increase carbon sequestration and expand renewable energy production. Through the programs, USDA hopes to cut net emissions related to agriculture by 120 million metric tons per year by 2025 – the equivalent of taking more than 25 million passenger vehicles off the road.
One of the 10 programs addresses soil health by promoting conservation tillage and no-till systems: It aims to increase the use of no-till systems to cover more than 100 million acres by 2025. Nitrogen stewardship is another program under the initiative.