- Author: Nastaran Tofangsazi and Beth Grafton-Cardwell, Department of Entomology, UC Riverside
With the detection of Huanglongbing (HLB) in California in 2012 and 22 additional cases reported during 2015 through June 2016 there is a major concern among citrus growers about the spread of this incurable bacterial disease. The vector of the disease, the Asian citrus psyllid (ACP), is a hardy insect with good dispersal capabilities and can be found in many southern California citrus groves today. With no direct cure for HLB at present, the only option for growers to combat the disease is to control the psyllid. This can prove difficult for conventional citrus growers with broad spectrum insecticides, but for organic citrus growers, which grow an estimated 7% of citrus in California, the task is even more difficult with the currently available options.
Entrust (spinosad) + oil, Pyganic (pyrethrin) + oil, and oil alone are currently the recommended and most widely used insecticide options for organic growers (UC IPM Guidelines for Citrus). While these insecticides are fairly effective in killing ACP if they make direct contact, the residual life of these pesticides is very short (days) compared to conventional insecticides (weeks to months). For example, in our petri dish studies, 10 fl oz/acre Entrust SC + 0.25% Omni supreme spray oil caused 89% mortality, 17 fl oz/acre Pyganic 5.0 EC + 0.25% Omni supreme spray oil caused 73% mortality and 0.25% Omni supreme spray oil caused 42% mortality when 1st-2nd ACP nymphs were exposed to treated leaves one day after application. Nymphal mortality continued to decline for the Entrust + oil treatment (69% mortality) and even more severely declined for Pyganic + oil (27% mortality) 3 days after treatment. In contrast, one-day-old residues of a conventional insecticide, the neonicotinoid 5.5 oz Actara (thiamethoxam), resulted in more than 95% mortality of nymphs and mortality remained high for more than a month.
Studies of grower orchard treatments confirmed laboratory studies that showed a short residual effect of organic treatments (Entrust + oil and oil alone) compared to conventional insecticides (Actara). We monitored changes in population densities of ACP (adults by tap, nymphs and eggs by flush examinations) in the fall of 2015 before and after a grower sprayed separate orchards with one of three insecticides; 1) 1.25% 440 Supreme Spray Oil by ground application (400 gpa), or 2) 9 fl oz Entrust SC + 1% oil by air (50 gpa), or 3) 5.5 oz Actara by air (50 gpa). The oil treatment had little effect on the adult population, but significantly reduced psyllid nymph densities for 17-24 days. Entrust was completely ineffective in controlling psyllid nymphs, but suppressed adult and egg populations for about 14 days. Actara, a conventional insecticide, was the most effective treatment in the study and provided more than 5 weeks of both adult and nymph control. Because of the short residual effect of organic insecticides in citrus, repeat treatments are needed at a frequency of about every 2 weeks for ACP control.
Tamarixia radiata wasps released for biological control of ACP provide 20% to 88% parasitism depending on geographical location and time of year. If there were no disease to be concerned about, this level of parasitism by Tamarixia would be sufficient to protect citrus from the feeding damage of the psyllid. However, the disease spreads rapidly with just a few psyllids and so a greater level of control is needed. Generalist predators, such as lady beetles, lacewings and assassin bugs, also assist with control. Argentine ants can severely disrupt this parasitism by protecting psyllids from natural enemies. Unhappily, Entrust + oil, thought of as a very selective insecticide combination, was found to be highly toxic to adult Tamarixia wasps exposed to 3 day old residues. Thus, the organic insecticide that is the best for controlling the psyllid pest is not compatible with the parasitoid natural enemy, limiting our ability to use integrated strategies to control the psyllid.
At present, it is not mandatory, but is strongly recommended, that all southern California citrus growers treat their orchards in an area wide manner. The area wide program consists of coordinated treatments twice a year (winter and fall), and additional treatments in between. Due to the short residual nature of organic insecticides, organic applications should be applied twice within 10-14 days of each other for every single conventional insecticide application. This is especially important for younger groves as ACP nymphs thrive in new flush. Organic growers have a tough decision to make between treating frequently for ACP and the high cost associated with those treatments or transitioning into conventional management in order to more effectively control ACP. Additional solutions are needed for organic citrus.
UC IPM Guidelines for Citrus: Asian Citrus Psyllid. http://ipm.ucanr.edu/PMG/r107304411.html
- Author: Cheryl Wilen - Area Wide IPM Advisor
There has been more than the usual number of questions about what I am calling "bio-based" herbicides recently. Arguably, this is coming from news that some school districts and cities specifically calling out the use of glyphosate on the properties they manage. Landscaping departments want to know which of the products available work the best.
To start, please be aware that all of these products are contact herbicides that will not move through the plant. Therefore, they will not be effective if you are trying to get to any underground organ such as the roots, rhizomes, tubers, etc. of any perennial plant. Do not try to make a head to head comparison to glyphosate - glyphosate will win every time. These act more like diquat (Reward) so if you are using Reward, some of these could be a good replacement, if needed.
Here's what I have in:
Suppress* |
CAPRIC ACID + CAPRYLIC ACID |
Finale |
GLUFOSINATE-AMMONIUM |
WeedPharm* |
ACETIC ACID |
AvengerAG* |
LIMONENE |
AXXE*,** |
AMMONIUM NONANOATE |
WeedZap* |
CLOVE OIL + CINNAMON OIL |
Burnout* |
LIMONENE |
Scythe |
NONANOIC ACID |
Fiesta** |
Fe HEDTA |
Roundup Pro |
GLYPHOSATE |
*listed as “organic” but not necessarily OMRI certified
**listed as a biopesticide
I also tried A.D.I.O.S. (active ingredient: sodium chloride + other ingredients: potassium chloride, sodium bicarbonate) in a preliminary experiment and found that it was a waste of my time.
The rates for most of these can be quite high. For example, WeedPharm is applied with no dilution even though it carries a “Danger” signal word on the label. Other are applied at 3-25% rates by volume.
- Author: Ben Faber
Because of potential contamination of mulches from pesticides, mulch use is being called into question and testing may be required for mulches applied to organic orchards. This is a recent ruling. As always, anything applied to a certified organic operation should be cleared with the certifier first.
http://www.prnewswire.com/news-releases/beyond-pesticides-federal-court-finds-usda-process-for-allowing-pesticide-contaminated-compost-improper-and-stops-use-300288112.html
- Author: Cheryl Reynolds
The UC Statewide Integrated Pest Management Program (UC IPM) put together a 26-page card set in English and Spanish on understanding pesticide labels. Intended for pesticide handlers, applicators, safety trainers, and pest control advisers (PCAs), the cards explain when to read the label, describe what kind of information can be found in each section of a pesticide label, and point out specific instruction areas so that applicators can apply pesticides safely and avoid illegal pesticide residues.
Traces of pesticide residue are normal and even expected after pesticides are applied to food crops, but by the time produce is ready to be sold, purchased, and consumed, residues are usually far below the legal limit.
by Cheryl Reynolds, UC Statewide IPM Program
In its latest report from 2013, the California Department of Pesticide Regulation (DPR) reported that there was little or no detectable pesticide residue in 97.8% of all California-grown produce. This demonstrates a strong pesticide regulation program and pesticide applicators that apply pesticides safely and legally. However, there have been instances in California where a pesticide not registered for a specific crop has been used unintentionally, resulting in illegal residues and eventually crop loss and destruction.
The Environmental Protection Agency (EPA) sets tolerances for the maximum amount of pesticide residue that can legally be allowed to remain on or in food.
DPR regularly monitors domestic and imported produce for pesticide residues and is considered the most extensive state residue-monitoring program in the nation.
The primary way pesticide applicators can assure that they make proper applications and avoid illegal pesticide residues is to follow the pesticide label. UC IPM's new card set was developed from information in the upcoming third edition of The Safe and Effective Use of Pesticides as well as Lisa Blecker, UC IPM's Pesticide Safety Education Program coordinator. Bound with a spiral coil, this eye-catching instructional card set was designed for both English-speakers and when flipped over, for Spanish-speaking audiences as well. UC IPM also plans to release a new online course on preventing illegal pesticide residues sometime late fall.
To download copies of the card set in English or in Spanish, see the UC IPM web site.
- Author: Ben Faber
As summer continues to heat up, keep in mind that regulations remain in effect to reduce the volatile organic compounds (VOCs) that can be emitted into the atmosphere by pesticides and other harmful chemicals and contribute to the amount of ozone or smog in the environment.
Calculators from the Department of Pesticide Regulation (DPR) that determine the VOC emissions from fumigant and non-fumigant pesticides before application are available to help growers, pest control advisers, and pesticide applicators comply with the regulations. The UC Statewide Integrated Pest Management (IPM) Program provides a link to these calculators from each of the treatment tables in the UC Pest Management Guidelines. Click on the Air Quality – Calculate emissions button.
Take steps to reduce VOCs. Avoid emulsifiable concentrate (EC) formulations as they release the highest VOC emissions. Pesticide control advisers and growers can also reduce VOC emissions by employing IPM practices such as using resistant varieties, traps, exclusion, and biological control. When using pesticides, spot-treat and seek low-emission materials. Solid formulations, such as granules or powders, are best.
Check the fact sheet on the DPR web site for the most up-to-date-information on VOC restrictions and regulations.