By Brent McGhie, Butte County Master Gardener, July 26, 2013
The University of California recommends the use of Integrated Pest Management (IPM) to control garden pests. The goal of IPM is to use the least harmful control method(s) that will be effective in managing a particular pest. Depending on the pest, these methods include one or more of the following: cultural controls, biological controls, mechanical and physical controls and chemical controls (pesticides). When using IPM, it is recommended that gardeners resort to the use of pesticides only as a last resort, after other control methods have been tried and found wanting.
Before using a pesticide, be certain a pest is the actual cause of the problem you are experiencing. For example, plants can be damaged by incorrect watering, poor drainage, accidental herbicide exposure, or physical damage from wind, hail, sun scorching and other weather-related factors. A decision should also be made on how much damage you are willing to tolerate. Minor surface blemishes on fruit caused by thrips are probably an acceptable alternative to pesticide use. Once it has been determined a pest is present and is causing a major problem, identify the pest and research alternative control methods. If you need help, your Butte County Master Gardeners can provide guidance in these areas. In most cases, even if a pesticide is utilized, a combination of measures will provide the best long-term control.
Once the decision to use a pesticide has been made, the next step is to choose the right pesticide. The University of California Pest Notes series is a good source of information for identifying the least toxic pesticides appropriate for a specific pest. Low toxicity pesticides include insecticidal oils and soaps as well as the microbial insecticide, Bacillus thuringiensis, which is effective against many caterpillars, but nontoxic to other animal life. Pest Notes are available from your local Master Gardener program (based at the UC Cooperative Extension Office) and online at the UC Statewide IPM Program website (http://www.ipm.ucdavis.edu/index.html)
Before purchasing a pesticide read the label to be certain the plant you plan to use it on is listed on the label. Never use pesticides designated for use on ornamental plants on plants that will be eaten unless they are also listed on the label. Also, be aware that most pesticides only control certain stages of a pest’s life cycle. For disease control it is important to remember that fungicides are preventive and, although they may slow the progress of an existing infection, they will not eliminate it. Herbicides may be pre-emergent (preventing weeds from germinating successfully), or post-emergent (designed to kill actively growing weeds). Herbicides may also be broad-spectrum (killing weeds of almost any type), or selective in the type of weeds they affect.
Whenever a pesticide is used, all instructions should be read and carefully followed. Especially critical are instructions concerning proper application and safety precautions (for example, the use of protective clothing and eyewear).
To minimize pesticide contamination of the environment, mix only what is needed for immediate use and never use more than what the directions recommend. To further limit environmental exposure, avoid widespread applications; instead, apply only to affected areas. Do not spray during windy conditions when pesticides can be blown away from their intended target. To prevent contamination of waterways, avoid spraying near storm drains, creeks, or other bodies of water. It’s important that the application dry on the target before it gets wetted by rain or irrigation. Unless otherwise specified, do not spray just before irrigating, or before rainy weather. Additionally, be aware that spraying pesticides on hard surfaces such as foundations, driveways or sidewalks increases the likelihood that they will be washed off into storm drains.
The only legal way to dispose of pesticides is to take them to a local hazardous waste disposal facility. Do not pour unused or excess material down the drain, onto the soil, into waterways, into gutters, or into the trash. However, in California it is legal for homeowners to dispose of empty pesticide containers in the trash. Before disposing, containers should be triple rinsed and the rinse water used as part of the last application. To find the location of the closest hazardous waste disposal site, call the California Environmental Hotline (1-800-253-2687), or visit the “Earth911” website.
Information in this article is based on “Pesticides: Safe and Effective Use in the Home and Landscape” at UC IPM Online (Pest Note #74126).
By Michele Carter, Butte County Master Gardener, July 12, 2013
Yellow starthistle seeds germinate from fall through spring, corresponding to the normal rainy season in California. After germinating, the plant allocates most of its resources to root growth and by late spring, roots can extend over 3 feet. The plant exists as a short rosette amongst other weeds until it begins to flower.
The foliage of this plant ranges from gray-green to blue-green; once flowering begins it can easily be identified by its bright, thistle-like yellow flowers, which have sharp spines surrounding their bases. This weed grows from 6 inches to up to 5 feet.
Yellow starthistle forms dense infestations and rapidly depletes soil moisture, preventing the establishment of other species. It is also poisonous to horses, causing a nervous disorder called “chewing disease” (nigropallidal encephalomalacia), which is fatal once symptoms develop. Horses are the only animal known to be affected – they should not be allowed to graze on yellow starthistle.
Yellow starthistle can be spread as a contaminant in grass seed and in all classes of hay, particularly grass hay. Hay used as mulch along roadsides or disturbed areas can be a source of yellow starthistle. Livestock that have fed in areas infested with yellow starthistle can be transporters of the seed.
Because the seeds germinate during the rainy season, a single cultivation after the rainy season, when soils are dry, effectively controls yellow starthistle seedlings and rosettes. Timing is critical: this cultivation must take place in late spring after the last rains but before seeds are produced.
Mowing can be used to manage starthistle. Be sure to mow well before starthistle is in full flower or has set seed. Mowing is most effective when soil moisture is low and no irrigation or rainfall follows mowing. If rain occurs after you've removed existing plants, seeds will continue to germinate and the eradication process must be repeated. Pre-emergent and post-emergent herbicides can also be helpful in controlling growth and infestation of starthistle.
Lastly, effective management of starthistle includes revegetation. Planting affected areas with desirable plants discourages starthistle regrowth by creating competition.
For information about herbicides and for photos of yellow starthistle's growth cycle, visit http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7402.html
By Michelle Ramsey, Butte County Master Gardener, June 28, 2013
If something is eating your tomato plants or your eggplants, hornworms may very well be the culprit.
Two common species of hornworms seen in the garden are the Tomato Hornworm (Manduca quinquemaculata) and the Tobacco Hornworm (Manduca sexta). They can be differentiated by how many white stripes the larvae have on each side of their bodies. Tobacco hornworm larvae have 7 diagonal stripes on each side, while the tomato hornworm larvae have 8 chevron-shaped stripes. Mature hornworm larvae can be very large, up to 4 inches long (they will most likely be the largest “caterpillar” you’ll see in your garden). Hornworms feed on blossoms, leaves and fruit and are particularly known to cause damage to tomatoes and eggplants. Damage to plants typically occurs in mid-summer (but may also be seen in late summer). In their larval stage, hornworms are green caterpillars often seen hanging upside down on the plants. They have a “horn” at the rear end of their body. In the early summer, hornworm eggs (laid singly on leaves), hatch into larva. The larvae feed on leaves for 3-4 weeks and then burrow into the ground to pupate. The pupa over-winter in the ground and then emerge as adult moths. Adult hornworm moths are strong fliers with a wingspan of up to 5 inches.
The larval form of the hornworm is the only stage that causes damage to your plants. Hornworms can be hard to find as their green coloring provides a nice camouflage for them amidst the tomato plant leaves. Foliage damage (and possibly some damage or scarring of fruit) and large droppings on the dirt under the plants are indications that hornworms are present in the garden. When the plant is shaken gently hornworms will sometimes make a clicking sound which can help you locate the intruder. Natural enemies of hornworms are the Trichogramma parasitic wasp which lays eggs in the hornworm eggs and the Hyposoter exiguae parasitic wasp which infests the hornworm larvae as a parasite.
The most common methods of hornworm management are hand-picking them off plants and/or snipping them with shears. However, if the hornworm infestation is out of control, an organic spray (Bacillus thuringiensis or Spinosad) may be applied. These sprays are effective against smaller hornworm larvae but will not destroy the natural enemies of the hornworms. Crop rotation and disking (breaking up and turning over the soil) after harvest destroys pupae in the soil, and will help prevent emergence and a repeat of the hornworm life cycle in your garden the following year.
For additional information visit:
http://www.ipm.ucdavis.edu/PMG/r783301111.html
By Michelle Ramsey, Butte County Master Gardener, June 14, 2013
We often experience ants in our homes when weather conditions change. They are typically looking for food, water, warmth, and/or protection from extreme weather conditions. Ants belong to the insect order Hymenoptera and are close relatives of bees and wasps. The most common outdoor ant found in California is the Argentine worker ant. The Argentine worker ant is approximately 3mm long, dark colored and does not sting. They have no natural enemies. Their colonies have multiple queens and only the queens lay eggs. An ant’s life cycle moves from egg to larva to pupa to adult. Their nests are normally found in moist soils, under debris or along sidewalks and driveways. Argentine ants are drawn to sweet foods but will also feed on protein (e.g. dead bugs). The Argentine ant will venture up to 100 feet away from the nest to find food, water and shelter inside buildings. Once inside, if ants find food, they will continue to invade until the food source is removed and/or the entryway sealed.
While it is not realistic to eradicate all ants from your backyard, you can effectively reduce the number of ants entering your home by following a 3-Step integrated approach as follows:
Minor Indoor Problem (small trail of ants observed infrequently). Prevent further intrusion by:
1) Identifying the location where the ants are getting into the house. Inspect baseboards, floors, electrical outlets, vents, pipes, drains and walls for any entryways and seal them off (caulk is good for this). Destroy any nesting sites found close to the house. Cut back trees, shrubs or wooded material touching the house and clear away mulch or debris that is next to the house.
2) Clean up food and water sources in the home. All sources of “attractive” food should be removed or securely sealed. Use soapy water to kill ants and eliminate their trails.
Moderate (trails of hundreds of ants) and severe (several hundred to thousands of ants continue to invade for weeks or months). Supplement steps 1 and 2 above with the addition of bait stations as follows:
3) Install bait dispensers around the outside of the house (UC Researchers have had success using bait dispensers such as KM AntPro Liquid Bait Dispenser). Baits are more effective and less toxic than traditional pesticide treatments for ants. Baits are insecticides mixed with materials that attract worker ants. The advantage of a bait station over an insecticide spray is that the spray only kills the worker ant while the bait station allows worker ants to take the bait back to the colony to feed and kill the colony ants, including the queen ant. When all the queens die, the colony is destroyed. Continue to refill dispensers regularly with liquid borate-based bait until the ant problem ceases. It is critical that you select the right bait/attractant for Argentine ants (liquid baits with 1% or less borate are suggested). Install at least one dispenser on each side of the house, next to structures where ants are trailing (but at least 5 ft. from any nest). Keep ant bait stations out of direct sunlight.
Following the 3-step approach above should correct home ant invasions.
For more information visit:
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7411.html
By Mahina Gannet and Jeanette Alosi, Butte County Master Gardeners, May 31, 2013
If you plan to travel this summer, now might be a good time to install an automatic watering system. Doing so can ensure that your plants will not be under-watered or over-watered in your absence.
An effective irrigation system will supply the right amount of water to each plant resulting in water savings and more healthy plants. It will reduce weeds and help prevent pest and disease problems from occurring.
Drip irrigation is the tool that can help you minimize water wastage and maximize water’s benefits to your garden. Drip watering is the frequent, slow application of water to soil through emitters or micro-sprinklers. Drip irrigation works well for vegetable gardens, ornamental and fruit trees, shrubs, vines, and outdoor container plants. Even without an automatic sprinkler system installed, a drip system can be set up using a standard garden hose attached to the main drip line.
Installation of a basic, simple drip system is quite straightforward, and easily within the grasp of most home gardeners. It goes together much like a tubular erector set, all snapping together. Main one-half-inch (1/2”) or five-eighths inch (5/8”) polyethylene tubing line connects to your water source (if you’re on well water, you need a filter on the water source). Drip emitters, microsprinklers, or ¼” spaghetti tubing with emitters can be installed off the main line using barbed connector fittings that poke into the main lines. Solid spaghetti tubing can also be attached to the main line with an emitter attached at the other end to provide water directly to the plant. Alternatively, main line poly tubing can be purchased with in-line emitters pre-installed inside the tubing. Both the main poly tubing line or the in-line emitter tubing can be snaked through your beds or circled around shrubs and trees to deliver water directly to your plants.
With a drip irrigation system in place, water will be delivered a) directly to the plants of your choice and b) directly to the roots of those plants. These two simple factors can lead to fewer unwanted weeds in the garden and help reduce plant diseases.
The second consideration for smart watering is consistency. An automatic watering system is extremely consistent because it runs on a set schedule.
The timing and amount of water you deliver depends on the plants to be watered and the soil type. Depending upon your soil’s density, water will move quickly or slowly through it. For example, water poured through sand will move very quickly because sand is loose rather than dense or compact. But water poured through clay will trickle very slowly. Consider the plant’s whole root structure within your particular type of soil. An effective water system will deliver water to the entire root structure. The goal is to water for deep, strong roots that that aren’t waterlogged.
This is where math becomes useful. Drip irrigation emitters release a certain amount of water per hour. You can calculate how much water you are delivering by employing simple multiplication and division; with that number, you can decide how long you need to run your irrigation. Decide on the amount of water required by the plants each watering cycle, calculate the amount of time needed to deliver that amount (gallons per hour per emitter x total number of hours = total gallons per emitter) and water for that amount of time.
Watering is an active relationship that requires constant adjustments. You may need to tinker with your system to make seasonal changes, fix broken pieces, and make adjustments for better efficiency.
While drip irrigation is a good way to achieve efficient watering, it is not absolutely necessary. What is necessary is analyzing your own plants and determining how to best meet their needs given your personal situation. If you are a gardener who travels frequently, implementing a reliable automatic watering system will reassure you that your plants will remain happy, well watered, and growing until you return.
A very helpful publication on this subject is the University of California Agriculture and Natural Resources (UC ANR) Publication 21579, “Drip Irrigation in the Home Landscape.”
