- Author: Jeannette Warnert
Weeds present a serious economic problem for farmers, a major headache for vegetable gardeners, and an unattractive appearance in landscapes, but herbicides are not the only solution.
“Studies have shown that more than 70 percent of weeds in lawns and ornamental plantings can be controlled based on good cultural practices,” said Dr. Clebson G. Gonçalves, a horticulture expert and farm advisor with UC Cooperative Extension in Lake and Mendocino counties. He spoke about springtime weed identification and management during a recent urban horticulture webinar offered by the UC Integrated Pest Management Program. “To control weeds, start with good soil; choose suitable plants; and mow, prune, water, and control pests to ensure dense and healthy turf and ornamentals.”
There are several definitions for the term “weeds,” but generally speaking, it can be defined as a plant out of place. Gonçalves used common bermudagrass as an example.
“Bermudagrass is one of the most desirable grass species for golf courses, sports fields, and residential lawns. But out of place, it's extremely difficult to control. It's adaptable to a wide range of environments and can reproduce by rhizome, stolon, and seeds,” he said.
When deciding how to control weeds in lawns and landscapes, Gonçalves suggests gardeners start by identifying the species. The Weed Research and Information Center at the University of California, Davis, offers a free online weed identification tool. Users input characteristics of the weeds – such as weed type (grasslike, broadleaf, woody), where the weed was found, leaf characteristics, stem characteristics, floral characteristics, life cycle, growth habit, etc. – and the tool offers potential species. The UC IPM Program maintains a weed photo gallery of species commonly found in California.
Knowing the species helps determine best practices for control. For example, nutsedge is a grass-like weed that develops nut-like tubers on the roots. The tubers are key to nutsedge survival. Dig deeply into the soil to remove the tubers on mature nutsedge roots. To limit tuber production, remove small nutsedge plants before they have 5 to 6 leaves.
Gonçalves suggests following the principles of integrated pest management to control the weeds by first considering practices that are effective and environmentally sound.
- Avoid bringing weeds into your garden and landscape in the first place. Gonçalves suggests using weed-free soil and compost. “It's better to spend a little more money up front when you buy topsoil and compost, than spending even more money later for weed control,” he said.
- Inspect plants at nurseries before bringing them home to see if there are any weeds in or under the pot.
- Clean the mower between lawns. “This is especially important for landscaping companies that work in different locations on the same day. It is important to clean all the equipment before starting in a different location.,” Gonçalves said.
- Never let weeds go to seed. “A lot of species – such as dandelions, bermudagrass, and annual bluegrass – can produce a new seed head very quickly,” Gonçalves said. “If you mow every other week, that's enough time for these weeds to produce new seed heads and disperse seeds. It's better to mow once a week or even more often to prevent the production of seed.”
- Soil aeration. “It's very important to alleviate soil compaction in established turf. You will have better water infiltration, greater nutrient availability and more oxygen underground, which promotes plant health and growth above and below the ground,” Gonçalves said.
- Don't leave soil exposed. Limit the area for weeds to grow by utilizing dense plantings. “When you have light and moisture, you have weeds coming up,” he said.
- Mow uniformly at a height of three inches or more. The tall and dense turfgrass canopy will shade the ground and prevent the germination of several weed species.
- Fertilize uniformly.
- Pulling weeds. “Every weed can be controlled by hand. If you have the time to pull by hand, that is recommended. There is some pleasure in pulling weeds. It can be used as therapy,” Gonçalves said.
- Mulches. Wood chips, stone, leaves or compost – especially on top of landscape fabric – can control weeds.
- Flaming. Very effective, primarily in the early stages when weeds are small in stature. But if they are aggressive weeds with strong taproots, such as dandelions and buckhorn plantain, they can grow back very quickly.
- Organic. Always use certified products. “Don't make homemade herbicides. They are still pesticides and can be dangerous,” Gonçalves said. Corn gluten meal is the only organic pre-emergent herbicide. Organic herbicides are available for consumers in different combinations and concentrations. “Vinegar-based herbicides can be very expensive, but other options such as citric acid-based, caprylic acid-based, clove-oil-based, or ammonium nonanoate-based can be more affordable and provide vinegar-like weed control,” Gonçalves said.
- Synthetic. “Many synthetic herbicides also are available for consumers. But the question is: Do you need it? Keep in mind that, all options presented above must be considered first before deciding to use herbicides,” Gonçalves said.
- In both cases, synthetic and organic herbicides are pesticides. Carefully read and follow the label directions.
- Author: Ben Faber
- Author: Lauren Fordyce
If you've used disinfecting wipes to clean surfaces in your home, an herbicide to control weeds in your garden, or insect repellents while on a hike, then you have used a pesticide. A pesticide is any material (natural, organic, synthetic, or even homemade remedies) that is used to control, prevent, kill, or repel a pest. Pesticides are designed to be toxic against certain pests like weeds, insects, or bacteria. But when they are not used properly, pesticides can also be toxic to people and pets, and harm the environment including water quality, pollinators, and natural enemies.
February is National Pesticide Safety Education Month, a time to raise awareness about pesticide safety. Keeping yourself, your family, and the environment safe from pesticides starts with reading and understanding the pesticide label. Below are some key things to look for and follow on the label.
- Where can you use it? Some pesticides can be used on both edible and ornamental plants, indoors and outside. But other pesticides may explicitly state that they should not be used indoors, on edible plants, etc. Always be sure the label states that it can be used where you intend to use it.
- Signal words. The signal words Danger, Warning, or Caution on a pesticide label indicate the immediate (acute) toxicity of a single exposure of the pesticide to humans. Pesticides with the signal word Danger are the most toxic. Look for products with the signal word Caution, as these pose less risk of toxicity.
- What should you wear to protect yourself? When handling most pesticides, you should usually wear a long-sleeve shirt, pants, closed-toe shoes, eye protection, and chemical resistant gloves (not gardening gloves). This prevents you from being exposed to the pesticide through your skin, eyes, lungs, or mouth. For some other pesticides, like insect repellents you apply to your skin, read and follow the label for specific instructions.
- How long after applying can you enter the treated area? For many home-use pesticides, you can enter the treated area when the pesticide has dried. Entering an area where the pesticide is still wet can expose you to those chemicals. Some pesticide products may state that you must wait a certain number of hours before reentering the area.
- When can you harvest treated produce? If you applied a pesticide to your edible plants it's important to know when it is safe to harvest and consume them. Many pesticides can be applied to edible crops up until the day of harvest, but some pesticides may require days or weeks to pass before it is safe to do so.
- How should you store the pesticide? Pesticides should always be stored in their original container with the lid tightly sealed, in a locked storage cabinet where children cannot access them. Improper pesticide storage can lead to exposure incidents, such as a child drinking a pesticide or spilling it on yourself.
Following the pesticide label can prevent unintentional pesticide exposure to people and pets. To prevent harm to the environment, you should also follow these general guidelines:
- Don't apply pesticides in rainy or windy weather. If it is actively raining and windy, or rain is expected, hold off on applying the pesticide. Applying during rainy or windy weather can cause the pesticide to be washed away, polluting stormwater and waterways. It can also cause drift, which is when pesticide droplets or dust move through the air. Drift can harm nearby plants, bodies of water, or people.
- Don't spray plants in bloom. Protect pollinators and natural enemies (good bugs) that feed on pollen and nectar by not spraying flowering plants.
- Dispose of pesticides at your local household hazardous waste (HHW) site. Pesticide containers that are partially or entirely filled should be taken to a HHW site to prevent environmental contamination. Empty, rinsed pesticide containers can be disposed of in the garbage or recycled if accepted in your area.
Happy National Pesticide Safety Education Month. Visit Pest Notes: Pesticides: Safe and Effective Use in the Home and Landscape to learn more about pesticide use and safety.
- Author: Lauren Fordyce
In February we recognize Valentine's Day, President's Day, and Black History Month, but did you know it is also IPM month?! Join us in celebrating by learning more about integrated pest management (IPM), how you can use it in your everyday life, and the pest management resources and information offered by UC IPM.
What is IPM?
Integrated pest management (IPM) is a more sustainable, environmentally friendly method for managing pests like insects, diseases, weeds, and unwanted wildlife. IPM can be used by anyone: homeowners, tenants, farmers, gardeners, janitors, groundskeepers, professional landscapers and pest control operators, and more.
IPM focuses on the long-term management of pests through prevention and monitoring. This reduces pests reaching damaging levels and becoming difficult to control or requiring pesticide use. One way pests can be prevented outdoors is by providing plants with proper care (water, sunlight, and nutrients). You can prevent pests from coming indoors by sealing gaps around windows and doors. Monitor for pests using tools like sticky traps, or visual inspection.
Once a pest becomes a problem, it must be correctly identified so the correct management solution can be chosen. Many pests can be managed without the use of pesticides. In IPM, we often choose nonchemical solutions first:
- Biological control: the use of natural enemies—predators, parasites, pathogens, and competitors—to controlpests and their damage. Some examples of natural enemies include ladybeetles, lacewings, and spiders.
- Cultural control: practices that limit pests from establishing, reproducing, and living where they're not wanted. These practices can include increased cleanliness, proper storage of food, good plant care, and well-maintained landscape irrigation systems.
- Mechanical or physical control: kill a pest directly, block pests out, or make the environment unsuitable for them. Examples include traps for rodents, mulches for weed management, and flyswatters for flying insects.
Pesticides can still be an important part of IPM, but they should be used in combination with nonchemical solutions for long-term management. Pesticides alone will not solve a pest problem or prevent pests from becoming a problem again later. When pesticides are needed, choose products that are less toxic. Less toxic pesticides are those that pose fewer risks to people, pets, the environment, and natural enemies like ladybeetles. Learn more about less toxic pesticides at https://ipm.ucanr.edu/QT/lesstoxicinsecticidescard.html.
Whether you are trying to control cockroaches in an apartment, weeds in the garden, or diseases on landscape plants, UC IPM has the tools and resources to help you using an IPM approach.
To learn more about integrated pest management, visit https://ipm.ucanr.edu/what-is-ipm/ or view our resources for managing specific home, garden, and landscape pests using IPM at https://ipm.ucanr.edu/PMG/menu.homegarden.html./h2>
- Author: Jeannette Warnert
A collection of small raised beds decorated with colorful scarecrows, quaint décor and several rabbit topiaries make up Mr. McGregor's Garden, but this one doesn't have mischievous Peter Rabbit nibbling on the fruit and vegetables. The main problem appears to be snails. Last fall, dozens of garden snails were found feeding on the leaves of napa cabbage, cauliflower, kohlrabi and broccoli plants.
The Master Gardeners have been searching for organic solutions to the problem. Picking them off one by one has been the first line of defense. The Farmers Almanac suggests spreading crushed egg shells to deter snails from garden beds, and we tried it. However, the UC Integrated Pest Management program reports that egg shells are an ineffective deterrent, and we have seen little improvement.
Another solution available to Fresno County gardeners are decollate snails. Decollates are small, thin, tapered and easy to distinguish from the familiar larger, rounded brown garden snails. The decollate is native to North Africa and the Mediterranean region. It was accidentally introduced to Southern California in the 1960s, and has since helped manage snails in gardens and agricultural settings throughout Southern California and parts of the San Joaquin Valley. It is legal to purchase and release decollates only in the California counties of Fresno, Imperial, Kern, Los Angeles, Madera, Orange, Riverside, Santa Barbara, San Bernardino, San Diego, Tulare and Ventura. Because of its potential adverse impact on certain endangered and native mollusks, they should not be used in any other places in the state. Even in counties were decollate snails are permitted, they should not be introduced in or near natural areas because of the potential danger to native snails.
“Literature says it takes four to eight years for decollate snails to control brown snails, but my experience is they'll clean them out in a year,” Woods said.
The decollates are easy to find throughout Woods' front and back yards, under rocks and plants and nestled in plant litter. In February, Woods donated about 30 decollate snails to the Master Gardener's Children's Garden. The decollates were dispersed among strawberry and vegetable plants. While not a scientific trial, our experiment may lead to fewer snail and slug pests and less leaf damage in the coming years.
Visit the UC Master Gardeners Children's Garden in the Garden of the Sun, 1750 Winery Ave., Fresno. Hours: 9 to 11 a.m. Monday, Wednesday and Friday.
Identify snail damage, UC IPM (YouTube video)