July 24, 2016
A final summary of the many lessons that surfaced during the five farm visits that were held back in May and June is now posted at the CASI website at http://ucanr.edu/?blogpost=21603&blogasset=85918.
Additional farm demonstration evaluations are being established and we hope to have more opportunities to share this work in the near future. If you are interested in becoming involved with the farm demonstration network, please contact us at (559) 303-9689.
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
What happens when two problematic invasive plant species hybridize? In the case of Salsola...
Citrus Clonal Protection Program Lindcove Research & Extension Center, University of California
When I started working at the Citrus Clonal Protection Program (CCPP) in 2012 (Fig. 1), citrus budwood was distributed three times per year (i.e. January, June and September) and there was a minimum order limit for 36 buds per order. In July of 2013, CCPP began monthly budwood distribution and essentially removed the budwood order limit offering as little as one budstick (6 buds). This was a game changer. In the following three years of monthly budwood distribution, the amount of requested buds has increased by almost 50% (Fig. 2), and most importantly, the orders placed by citrus hobbyists has increased by almost 80%. Citrus hobbyists are growing citrus for non-commercial purposes. Many of the hobbyists have a small “citrus forest” in their backyards, typically of diverse varieties, and they are very proud of their trees. They are typically not interested in purchasing grafted citrus trees, they want to graft their own citrus trees. It is hard to understand the citrus hobbyists' deep affection for their trees! I grew up in a citrus family farm and for me, citrus was as any other crop, a plant for profit. However, after interacting with the citrus hobbyists over the past several years, I have gained a level of respect and understanding that the passion citrus enthusiast have.
I had always been taught that citrus hobbyists are a threat to the citrus industry and their capacity to propagate citrus should be limited or denied. This line of thinking has resulted in some citrus production areas to restrict citrus budwood access for non-commercial use. Today, I see that ignorance is the true threat to the citrus industry. People usually don't understand or comprehend that smuggling plants or plant parts can disseminate diseases and cause severe economic damage to the farmers. Restricting the desire to propagate a citrus variety may force someone to smuggle it. A sad example is Huanglongbing (HLB) in California. This imminent threat to the California citrus industry was first found in a back yard citrus tree that had 23 grafts of unknown budwood origin.
The California HLB/Asian Citrus Psyllid prevention campaign is doing an excellent job of educating the public. Also the University of California Cooperative Extension is teaching Master Gardeners about the dangers of smuggling plants. On the Internet, there are individuals, such as the pomologist-writer “Fruit Detective” and the citrus hobbyist-blogger “Fruitmentor”, educating people on the correct way to propagate citrus and providing information regarding the threat of importing budwood that that may contain pathogens that could effects citrus production locally. Thanks to this multi educational effort, many citrus hobbyists are now part of the solution and they are actively engaged in the effort to protect the California citrus.
CCPP has over 300 citrus varieties available to anyone interested in propagating citrus trees for commercial or personal use. Orders can be as small as 6 buds (one budstick) per variety at $ 4.50. Therefore, the CCPP offers the incentive to use inexpensive-easily purchased- tested budwood over smuggled or exchanged “dirty” citrus budwood.
Despite all of the above, I still strongly recommend to purchase grafted trees at local stores or online (e.g.
www.fourwindsgrowers.com). Grafting citrus is not as easy as it may look. It requires skill, another citrus tree to be used as a rootstock, and a controlled environment (especially
temperature and water). However, if you are going to do it yourself, make sure the material your using is disease free!
To learn more about the CCPP, go to www.ccpp.ucr.edu and remember: CCPP is the place for starting citrus correctly.
Panoramic view of the Citrus Clonal Protection Program foundation block operations at the Lindcove Research and Extension Center, Exeter, California. Photo: E. Grafton-Cardwell.
Matcha, finely ground powder made from baby green-tea leaves, is growing in popularity due to health benefits and the natural woodsy flavor it imparts to drinks, pastries and savory dishes, reported Jenice Tupolo and Carla Meyer in the Sacramento Bee.
To find out if the most-prized tea in Japan lives up to its purported health benefits when scrutinized scientifically, the reporters contacted UC Cooperative Extension specialist Sheri Zidenberg-Cherr.
“The health benefits are similar to that of green tea in general,” Zidenberg-Cherr said. Possible benefits of green tea include lower risk of cardiovascular disease and some types of cancers, and bone-density improvement. Though "the studies are pretty inconclusive," she said, some have been promising.
"Some have shown a benefit of maybe three cups a day in terms of reduced risk of cardiovascular disease especially," she said.
Zidenberg-Cherr cautioned against taking matcha or green tea with dairy milk.