Posts Tagged: resistance
UCCE water management expert helps save water, increase supply in SoCal
Earlier this year, officials in Southern California declared a water shortage emergency resulting in restrictions such as limiting outdoor water use to one day of the week. While mandatory restrictions vary across the region, Amir Haghverdi, UC Cooperative Extension specialist and associate professor of agricultural and urban water management at UC Riverside, is using research to pinpoint irrigation strategies that will help communities reduce their demand for water and increase supply.
Haghverdi and his team are responding to a hotter and drier California by working to identify changes that can make a substantial difference in water savings.
While behavioral changes such as preventing leaks and turning the faucet off while brushing teeth can help, Haghverdi's research focuses on methodical changes like stressing green spaces, planting drought-tolerant plant species, using non-traditional water sources, and investing in technology to better control water use.
Testing a lawn's limits
For six years, Haghverdi and his team have performed stress tests on turfgrass to identify the lowest percent of evapotranspiration rate (ETo) that it can withstand and still survive. To do this, Haghverdi's team applies different percentages of ETo, obtained from weather stations, and monitors the performance of each landscape species over time.
While both cool-season and warm-season species can be stressed and still maintain their aesthetic value for a few weeks to several months, Haghverdi's results showed that warm-season turfgrass species require less water and can withstand water stress better.
The actual duration that people can apply less water depends on the type of turfgrass, the weather conditions and the stress level. For example, results showed that hybrid bermudagrass (a warm-season turfgrass) during summer in inland Southern California could keep its aesthetic value above the minimum threshold for 30 to 50 days, depending on the weather conditions, with irrigation application as low as 40% ETo.
In contrast, tall fescue, a cool-season turfgrass, even with 20% more water, showed signs of stress after only a few weeks and could not maintain its minimum acceptable quality.
Plant drought-tolerant species
Haghverdi's work demonstrates that when water conservation is the goal, alternative groundcover species are clearly superior to all turfgrass species and cultivars that they have tested so far. In fact, his team has identified drought-tolerant species that can maintain their aesthetic values with a third to a quarter less water than cool-season turfgrass (as low as 20% ETo) and can even withstand no-irrigation periods.
Furthermore, extensive field trials showed that new plant species from different regions could be as resilient as native species in withstanding drought and heat stress while maintaining their aesthetic beauty and cool canopy. Occasionally, they have outperformed native species, underscoring the advantages of drought- and heat-tolerant species that are non-native.
Based on Haghverdi's preliminary results for minimum irrigation requirement in inland Southern California, creeping Australian saltbush, a non-native species originally from Australia, and coyote bush, native to California, were top performers. Considering cooling benefits, drought tolerance and sensitivity to over-irrigation, creeping Australian saltbush performed the best.
Counties are already using recycled water
Although he recommends renewing your landscape with drought-tolerant or low-water use greenery and identifying how long your green spaces can live without water, Haghverdi acknowledges that, while contradictory, the cooling benefits of landscape irrigation are essential in Southern California.
“This is one of the tradeoffs of water conservation,” said Haghverdi. “If the only goal is to conserve water, maybe people will conclude that we don't have enough water to irrigate landscape.”
Water conservation efforts could influence counties to stop or reduce landscape irrigation. The consequences, however, would result in hotter environments due to the heat island effect. The loss of landscapes means that the sun's energy will be absorbed into the ground, instead of prompting transpiration in plants, which helps keep environments cool.
Thus, stressing green spaces and investing in drought-tolerant plant species help reduce the demand for water, but increasing water supply is just as vital. Haghverdi urges Southern California counties to prioritize a supplemental water supply such as recycled water – an approach already implemented in Ventura, Orange and San Diego counties.
The Metropolitan Water District of Southern California's Pure Water Southern California Program, formerly known as the Regional Recycled Water Program, aims to do just that. In partnership with the Los Angeles County Sanitation Districts, the program will further purify wastewater to produce a sustainable source of high-quality water for the region.
According to the program's website, this would “produce up to 150 million gallons of water daily when completed and provide purified water for up to 15 million people, making it one of the largest water reuse programs in the world.”
Smart controllers save time, money and water
Making the best use of the water you already have relies on efficiency. Sprinklers that are poorly placed, for example, are not as effective as they could be.
“What I see often while walking my dog in the neighborhood is that there's a lot of runoff, bad irrigation and bad timing like when it's windy,” Haghverdi observed. “People usually set their irrigation timer and then forget it, but they don't adjust it based on the season or weather parameters. That's not going to help us conserve water, a precious resource, in California.”
Thankfully, Haghverdi and his team have done extensive research on smart irrigation controllers, which, simply put, are irrigation timers with a sensor built in. Generally, there are two types of smart irrigation controllers: weather- and soil-based controllers.
Weather-based controllers use evapotranspiration data to automatically adjust their watering schedule according to local weather conditions. Soil-based controllers measure moisture at the root zone and start irrigating whenever the reading falls below a programmed threshold.
Smart controllers that have flowmeters can detect leaks and be activated automatically, whereas rain sensors can stop irrigation during rainfall. Although both additions are ideal for large irrigation landscapes such as parks and publicly maintained green spaces, rain sensors are easy to install and effective for residential areas too.
When asked about cost being a hindrance, Haghverdi responded, “Not a lot of people know that there are grants for smart controllers – some that will pay either all or a majority of the cost.”
To check if grants are available in your area, interested individuals are encouraged to contact their local water provider.
“We need to move towards autonomous and smart irrigation [strategies], and water management in urban areas. That's the future. If we can build autonomous cars, why can't we build smart water management systems that apply the right amount of water to each plant species, can detect leaks and prevent water waste?” said Haghverdi.
To learn more about or stay updated on Haghverdi's research, visit www.ucrwater.com.
Insecticide resistance in alfalfa: the basics, why it matters, and what can you do?
Insecticide resistance in alfalfa weevils is spreading across California Insecticide resistance is “alive and well” in alfalfa....
Controlling Alfalfa Weevils in the Intermountain Area with Pyrethroid Resistance
Picture 1: Adult alfalfa weevil Alfalfa weevils, key pests of alfalfa hay, have been showing pyrethroid insecticide resistance within the...
New online course helps PCAs manage pesticide resistance
manage the problem. Resistance develops when the same type of pesticide is used repeatedly and frequently to control a pest. Every pest population contains individuals that vary genetically in some way; some vary in their susceptibility to being killed by a particular pesticide.
When a pesticide is applied, some individual insects or weeds are killed and others are not. The individuals that are not killed vary genetically from the ones that were killed, and when they reproduce, their offspring are also likely not to be susceptible to the pesticide. Over time, the population changes and you are left with the genetically resistant individuals as the majority of the population. Resistant pests can result in higher pesticide rates being applied and more frequent applications. We see resistance occurring in weeds, insects and pathogens.
Pest control advisers and growers are often the first to see what is going on in the field. After a pesticide is applied, they may be the first to report back to researchers if the application was effective or not. If they see patterns of decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest, they may conclude that resistance is occurring. Pesticide resistance is the topic of a new online course developed by UC IPM that can help PCAs and other licensed pesticide applicators recognize resistance when it is occurring, discover how it developed, apply practical methods of managing it and delay its occurrence.
The new online course covers resistance within the disciplines of plant pathology, entomology and weed science. It is based on a series of workshops on resistance management held in Davis, Fresno and at the UC Kearney Agricultural Research and Extension Center during the spring of 2014 presented by UC Cooperative Extension specialists Doug Gubler (Dept. of Plant Pathology, UC Davis.), Larry Godfrey (Dept. of Entomology and Nematology, UC Davis), Beth Grafton-Cardwell (Lindcove Research and Extension Center and UC Riverside Dept. of Entomology), and Kassim Al-Khatib (UC Statewide IPM Program).
There are several mechanisms through which pests become resistant to pesticides. One mechanism common to all three disciplines is target site alteration, where the site a pesticide normally attacks is somehow altered and no longer allows a pesticide to bind and affect the pest. Metabolic resistance is another mechanism, where pests detoxify or break down the chemical before it can work.
Although some differences occur in delaying or managing resistance across the disciplines, the key is to try to avoid intensive applications of pesticides so as not to allow resistant pests to become the majority of the population. Good IPM practices can reduce the need for pesticide applications. Rotating chemicals with different modes of action can also help manage resistance.
For an in-depth look at pesticide resistance, check out the new course at http://www.ipm.ucanr.edu/training/pesticide_resistance.html. This course has been approved for two continuing education units in the “Other” category from the Department of Pesticide Regulation.
Chron helps distribute UC fire information
The Sweat Equity column in the San Francisco Chronicle today steered readers to a UC PowerPoint presentation on the Web that provides details on fire-resistance ratings for roofs.
Produced by UC Cooperative Extension wood durability advisor Steven Quarles, the 18-slide presentation gives viewers an understanding of how roof coverings get their fire rating.
The information in Sweat Equity, a regular home improvement column written by brothers Bill and Kevin Burnett, was prompted by a reader question about whether an existing shake roof can be treated for improved fire resistance. In short, the answer is no.
Roofing systems are fire-rated either A, B, C or not ratable, with A the highest rating, or most fire resistant, according to the article.
If homeowners wish to preserve the woodsy and casual appearance of a wood shake roof, the Burnetts said the existing shakes should be replaced with new fire-retardant pressure-treated wood shakes. Alone, the pressure-treated shakes result in a class-B roof covering; in conjunction with an underlying fire barrier material, such as this gypsum or fiberglass, the roof is class A.For more information on improving homes' fire resistance, see Quarles' Homeowners Wildfire Mitigation Guide online.
When new, an asphalt composition roof has a class A rating.