The environment is just one of many factors that influence the intensity of a pest or disease outbreak. Increases in temperature and changes in precipitation patterns are already sparking new conditions and affecting incidence of pathogens and the geographic distribution of diseases. This will be exacerbated as climate change becomes more intense.
“We see shifts everywhere. You constantly hear about new diseases showing up that weren’t in an area before. Some of that may not be climate change; it may be pathogens moving via global trade, coming in on a crate or something,” said Lindsey du Toit, Washington State University plant pathologist. “Just because a new disease shows up that hasn’t been there before doesn’t mean it’s the result of climate change. But certainly, climate change can influence the degree to which the newly introduced pathogen takes hold and flourishes.”
In the Northeast, climate change has caused a 72 percent rise in heavy precipitation events. “That’s pretty tough on farming,” said Cornell University’s Mike Hoffmann, professor in the Department of Entomology. Because the growing season is now longer, thanks to more frost-free days, it seems logical to plant some crops earlier. However, this can be complicated by intermittent wet and cool periods in the spring that set the stage for pathogens like late blight to take hold and wipe out early tomato crops. This is one example of a pest that has been aggravated by changes in conditions.
9 Tips For Adapting Faster Than Pests and Pathogens
- Monitor your fields for pest infestations.
- Diversify; spread the risk.
- Make sure all interventions make economic and environmental sense.
- Reach out to university Extension specialists to learn how to monitor, assess and identify pests and pathogens early. This will help you prevent populations from exploding and becoming difficult to manage.
- Improve soil health.
- Rotate to nonsusceptible crops.
- If your state Extension programs are not offering regional monitoring, encourage it.
- Find tools online at climatesmartfarming.org/tools.
- Invest in a predictive tool like the Network for Environment and Weather Applications.
“Farming’s already risky,” said Hoffmann, who advised that as the weather gets more unpredictable and more challenging and creates greater unpredictability in pest infestations, farmers become more diligent, engage in more careful observation, more scouting and more precision application of pesticides as needed.
Higher temperatures will affect the efficacy of some pesticides so that also must be monitored. “If you spray one day and it rains for the next three, obviously that’s another complication to be aware of,” he added.
Insects, pests and pathogens are often tied to a specific phenological stage of the plant. Thus they attack flowers, shoots, fruits or leaves. According to Peter Oudemans, plant pathologist at Rutgers University, pests adapt to specific geographic regions, microclimates and even plant genotypes. Oudemans reported more range expansion among pests that attack cranberries and blueberries. As an example, cranberry plants begin to flower based on temperature and photoperiod, whereas pathogens respond more to temperature. Therefore as temperatures increase during the spring months, the fungi develop with flowers and are better able to infect. “We are definitely seeing higher rates of infection by certain diseases,” he said.
Oudemans focuses on developing better ways to control disease of plants. With blueberries, he and his colleagues use a phenology-based management system and have developed a blueberry calculator to predict key developmental stages.
Although this and other tools exist to help produce growers adapt as pests and pathogens adapt to climate change, du Toit, Hoffmann and Oudemans are in agreement that the key component to farming success in a changing climate is footprints in the field.
“[Climate] change is happening, so you can’t just look at your calendar,” said Oudemans. “You need to be out there watching what’s going on and not be afraid to report new things. It is likely that we will see new pests. Brown marmorated stink bugs, boxwood blight, spotted wing drosophila, Phytophthora ramorum and emerald ash borer are examples of invasive species that we have seen. With climate change, we could see range expansions of insects like the southern pine bark beetle more frequently. Most of these problems need to be addressed by cooperation among grower, foresters, government and university Extension programs. Organisms follow the food supply not property lines or county/state boundaries, so we really need to communicate and work together.”
“Growers need to be scouting, not just for things they know [tend to] show up, but also for new diseases that they haven’t seen before,” said du Toit. “Some of the best growers I work with are those who go to commodity meetings, not just in their area, but the national meetings, the national allium research conference or the international spinach conference. They learn about what’s happening in other areas and become aware of diseases or pests that they might not have had to deal with, but might now start to see in their region because of the influence of climate change on which organisms can become more problematic.”
Du Toit added some of the best growers she has worked with don’t just scout their own fields; they contact her if they hear about a problem that happened in another area to determine whether it’s something they should scout for in their area. “I really think that the growers who tend to be most successful are those who are aware of what could be coming down the road,” she said.
Across the United States, organizations and Extension agencies offer predictive tools for pests, infestation and timing. In the Northeast, a system of weather stations known as NEWA (Network for Environment and Weather Applications) are available for purchase. NEWA stations provide day-to-day forecasts, linked to three or four dozen models on pests, pathogens and other weather-related concerns. NEWA provides relevant information to fruit and vegetable growers as the climate changes and risks from pests increase. (Find more information at http://newa.cornell.edu.) NEWA users reported that, as a direct result of using NEWA pest forecast models, they save, on average, $19,500 per year in spray costs and prevent, on average, $264,000 per year in crop loss.
In Oudemans’ opinion, the key to responding to climate change for agriculture is adaptability. He said, “If your farming practices are set in stone you will probably fail.”