We're excited to let you know that we've launched the new, mobile-friendly format of the Pest Management Guidelines: Avocado!
Please note that the content of the Pest Management Guidelines (PMGs) has not changed. The design has been changed to be more compatible with mobile devices.The new format will also help us to update information more efficiently since the content has been moved into a database. UC IPM team has reviewed each and every page to ensure the content (text, photos, and table information) was not changed during this process. During the reformatting, we have included hyperlinks to our new webpage Natural enemy releases for biological control of pests.
Cluster of healthy young avocado fruits and flower buds on tree. Petr Kosina credit
How do wildfires affect the health and safety of people in agriculture?
Farmers and farmworkers are at a greater risk for exposure to wildfire smoke, ash, and chemical residue due to their work outdoors and long shifts, both during an active fire as well as during cleanup and recovery. Due to the nature of agricultural work, it is difficult for farmers and farmworkers to stop working due to wildfires. Lost workdays and the potential destruction of crops can have an economic effect on both farmers and workers.
Regardless of their proximity to wildfires, agricultural workers can struggle with stress and other mental health issues related to the effects of wildfires. Income, access to healthcare, and immigration concerns increase the vulnerability of the farmworker population.
When a wildfire occurs, what protections and information are employers required to provide to employees?
The newly adopted regulation §5141.1 “Protection from Wildfire Smoke,” which went into effect on July 29, 2019, uses the local air quality index (AQI) for PM2.5 to determine when worker protections are needed.
If employers reasonably anticipate that employees may be exposed to wildfire smoke, they must:
What is included in the wildfire smoke safety training and resources provided by WCAHS?
WCAHS provides safety resources on wildfire smoke for both employers and employees. An employer checklist outlining the above action items is available in English and Spanish. For training purposes, a double-sided poster and accompanying discussion guide are available in English and Spanish and are useful tools for tailgate trainings and safety reminders in the workplace.
WCAHS is developing an in-person training for agricultural employers and employees that provides a more comprehensive and in-depth review of the health effects of wildfire smoke exposure, worker protection procedures, and more.
Find out more about the Western Center for Agricultural Health and Safety and the Training Program Schedule: https://aghealth.ucdavis.edu/wildfires/h2>/h2>/h2>
Passion fruit is widely grown and valued throughout the tropics and subtropics. Most Passifloras are vines which can climb to 20 or 30 feet. The fruit varies in color from purple to yellow-orange and in shape from an egg to a tennis ball. Inside its quarter-inch protective rind are numerous small seeds covered by a juicy aromatic, sweet-acidic pulp. The sweeter species are esteemed as a fresh fruit. The seeds are consumed with the pulp. The fruit is more commonly made into juice and often blended with other juices such as orange. The fruit also is used to make excellent ice creams, sherbets, jellies, and pies. The downside of the passion fruit is that most esteemed species are very frost tender. The best adapted to California of the subtropical species, the purple granadilla (P. edulis), is prone to a fusarium soil disease. However, there is a yellow form which, though not as sweet, is not subject to this disease. More importantly, the yellow form can be hybridized with the purple or used as a rootstock. The crop grows mainly along the coast where it enjoys the mild weather.
The purple ‘Frederick' variety is probably the most widely grown commercial variety in California. It's great tasting, and I've been known to suck the delicious innards of 15 fruit at a sitting. Aside from fusarium wilt, it has few pests or diseases. That was until this fall when fruit spotting started showing up on fruit and leaves. The cause is a fungus – Septoria spp. – which thrives in cool, moist conditions. These were exactly what we had this year. All summer long, there was fog along the coast, and this is what the fungus enjoys. It colonizes leaves, defoliating the plant and spreading to the fruit, causing Septoria Blotch (Spot). Once infected there's not much that can be done, other than preventing further spread to the rest of the vineyard.
Photo: Fruit Blotch
Fungal structures (pycnidia) growing on leaf, causing scarring spots
- Leaves are the most affected organs, showing light brown slightly round necrotic spots normally encircled by a chlorotic halo. A single lesion per leaf is sufficient to cause abscission, and even leaves without visible symptoms may fall prematurely.
- When the disease reaches 15-20% of leaves in the same plant, partial or even complete leaf abscission is observed. In young twigs, lesions may promote girdling leading to wilt and twig tips death.
- Lesions on flowers are similar to those on leaves. The primary infection in the calyx may reach the stalk, causing the early drop of flowers. The infection may occur at any stage of the development of the fruits, affecting maturation or development.
- Leaf and fruit abscission, twig wilt and plant death may occur under disease favoring conditions.
Treatment: Under ideal conditions and forehand knowledge!!!!
1) Rake up infected leaves on the ground and bury or compost more than 50 ft away from the vines.
2) Pick off spotted fruit and leaves and remove from field as soon as possible as spores are being produced in the lesions and can infect surrounding leaves and fruit when moisture is present.
3) During periods with dew, rain or ocean mist, spray Abound (azoxystrobin) or generic version of this fungicide on the vines. It distributes well over the foliage and fruit, is fairly rainfast, and gives about 2 weeks' protection.
4) To minimize the risk of the fungus developing resistance to Abound, apply a copper fungicide between Abound sprays, for instance Cueva (copper octanoate) is a good product and approved for organic production. Copper is a protectant and needs good coverage to be effective. It provides about 7 days of protection, possibly longer without rain.
So this year has been weird. Most years are. Lots of rain, no freezes, but it was a cold winter. Then all this fog in the summer that normally clears up going into summer. it seems like there's always something new. Had that funny scale on citrus again this year - wax scale - And the effects of fire can always bring a round of new pests. And there is always a new winter waiting for us.
Photo: Leaf and fruit spotting (blotch) from Septoria.
Biological control is the management of pests and their damage by the beneficial action of parasites (parasitoids), pathogens, and predators. These beneficial organisms, collectively, are named natural enemies.
Conserving (or protecting) and releasing natural enemies are important components of integrated pest management (IPM). In most situations, employing practices that conserve natural enemies is more effective, and less expensive and time consuming, than purchasing and releasing them.
Learn about the specific situations where purchasing and releasing parasites and predators can increase the effectiveness of biological control. Before purchasing natural enemies, consult the University of California (UC) IPM Pest Management Guidelines for that crop to learn whether UC research has shown that releasing them is effective. Some natural enemies on the market have never been demonstrated to effectively control any agricultural pest in California.
Obtaining Natural Enemies
Natural enemies can be purchased directly from various producers (companies that rear them) and suppliers (companies that purchase from producers and repackage and resell them). Some sources of parasites and predators are members of the Association of Natural Biocontrol Producers (ANBP). All ANBP members formally agree to a code of ethics and standardized methods.
Natural enemies purchased by users are commonly delivered via shipping services. Purchase parasites and predators only from in-state providers. It is illegal to obtain insects and other arthropods outside of California and carry or have them shipped across state lines without a permit from agricultural officials. Some pest control advisers and pest scouts will procure and release natural enemies as a service for growers.
Methods for Releasing Natural Enemies
Two methods for releasing natural enemies are inoculation and inundation:
- Inoculation—relatively few natural enemies are released. The offspring of these natural enemies provide biological control, not the individuals released.
- Inundation—large numbers of natural enemies are released, often several times over a growing season. The natural enemies released, and possibly their offspring, provide biological control.
The mealybug destroyer is an example of a natural enemy that is only released through inoculation—at relatively low numbers once per year early in the growing season. Aphytis melinus and Trichogramma parasites are released by inundation—at regular intervals over the growing season—to control California red scale and eggs of pest moths, respectively. Both inoculation and inundation can be used with predatory mites, depending on the situation.
Releasing Natural Enemies Effectively
Releasing natural enemies is most likely to be effective in situations where: 1) University of California researchers or other pest management experts have previously demonstrated success and 2) some level of pests and their damage can be tolerated in that crop. Desperate situations are not good opportunities for releasing natural enemies. Pests or their damage may already be too widespread for any release of parasites or predators to prevent economic loss of crop quality or quantity.
Increase the likelihood that natural enemy releases will be effective by
- Accurately identifying the pest and its natural enemies.
- Learning about the biology of the pest and its natural enemies.
- Releasing the appropriate natural enemy life stage and species.
- Releasing when the pests' vulnerable life stage(s) are present and at numbers that can be controlled by natural enemy releases.
Natural enemies are unlikely to be effective when released as if you were applying a pesticide. Instead, anticipate pest problems and begin making releases before pests are too abundant or economic damage is imminent.
- Remember that natural enemies are living organisms that require food, shelter, and water. Protect them from extreme conditions. For example, release them at night or early in the day during hot weather.
- Avoid applying broad-spectrum, residual (persistent) insecticides and miticides, and in some situations certain systemic or other pesticides, before or after releasing natural enemies. When needed, use pesticides selectively. For example, spot spray only where pests are abundant but localized.
Common reasons for the lack of satisfactory biological control after releases include the
- Application of broad-spectrum, residual insecticides, or in some situations systemic or other pesticides, prior to or after a release.
- Incorrect timing of release.
- Release of the wrong natural enemy for the pest situation.
- Release of a natural enemy species that is known to be ineffective.
For information on the use of biological control, see the UC IPM Pest Management Guidelines for your crop and specific pests. Most crops have a table called “Relative Toxicities of Insecticides and Miticides to Natural Enemies and Honey Bees” in the “General Information” section. Use these resources to guide pesticide selection to conserve natural enemies and improve biological pest control.
- Association of Natural Biocontrol Producers, Clovis, CA
- Grower Guide: Quality Assurance of Biocontrol Products (pdf), Vineland Research and Innovation Centre, Ontario
- Insectary Plants
- Natural Enemies Gallery
- Natural Enemies Handbook: The Illustrated Guide to Biological Pest Control
- Protecting Natural Enemies and Pollinators
- UC IPM Pest Management Guidelines
This Page is duplicated from the UC Integrated Pest Management website - https://www2.ipm.ucanr.edu/agriculture/natural-enemy-releases-for-biological-control-of-crop-pests/
Photo of predatory" mealybug destroyer" or Cryptolaemus
It has been a struggle to get through the summer this year. Weird. Hot. Then fog in August. Hot. Then fog in October. It's supposed to be clear,, blue skies in October. perfect weather for avocado persea mite and citrus leaf miner. Hot times then cooler. How to irrigate? A lot of folks just decided not to irrigate. Why do it when it's so crazy? Forecast was for no rain, but it's cool. And then it rained, and suddenly that beautiful citrus that has just broken color and is an orange globe, splits. It's most common in navels, but all citrus that ripen in the fall – tight-skinned satsuma mandarins, early clementines, tangelos and blood oranges. With the hot summer, it seems that a lot of citrus fruit have accelerated their maturity and are ready, ripe and sweet right now, and maybe ready to split.
And that's the problem. Drought stress. Salt stress due to drought. Water stress due to miserly watering. A heat wave in July. And a weird fall with maybe rain and maybe no rain and is ¼ inch considered rain or just a dedusting? Irregular watering is the key to splitting this time of year. The sugar builds, the pressure to suck in water builds and the fruit has been held back by a constrained water pattern and suddenly some water comes and it goes straight to the fruit and Boom, it splits.
Years of drought, and a stressed tree are a perfect set up for a citrus splitting in fall varieties like navel and satsuma. The days have turned cooler and there's less sense on the part of the irrigator to give the tree water and suddenly out of nowhere, there is rain. That wonderful stuff comes down and all seems right with the world, but then you notice that the mandarin fruit are splitting. Rats? Nope, a dehydrated fruit that has taken on more water than its skin can take in and the fruit splits. This is called an abiotic disorder or disease. However, it's not really a disease, but a problem brought on by environmental conditions. Or poor watering practices.
Fruit that is not yet ripe, like ‘Valencias' and later maturing mandarins are fine because they haven't developed the sugar content and have a firmer skin. They then develop during the rainy season when soil moisture is more regular. Or used to be more regular. With dry, warm winters this may become more or a problem in these later varieties, as well.
Several factors contribute to fruit splitting. Studies indicate that changes in weather, including temperature, relative humidity and wind may exaggerate splitting. The amount of water in the tree changes due to the weather condition, which causes the fruit to shrink. Then with rewetting, the fruit swells and bursts. In the navel orange, it usually occurs at the weakest spot, which is the navel. In other fruit, like blood orange, it can occur as a side split, as seen in the photo below.
Proper irrigation and other cultural practices can help reduce fruit spitting. Maintaining adequate but not excessive soil moisture is very important. A large area of soil around a tree should be watered since roots normally grow somewhat beyond the edge of the canopy. Wet the soil to a depth of at least 2 feet, then allow it to become somewhat dry in the top few inches before irrigating again. Applying a layer of coarse organic mulch under the canopy beginning at least a foot from the trunk can help moderate soil moisture and soil temperature variation.
Once split, the fruit is not going to recover. It's best to get it off the tree so that it doesn't rot and encourage rodents.
(Photo by Ottillia “Toots” Bier, UCR)