Many people seem to have problems during the winter with their citrus trees. There is a phenomenon that affects citrus grown in containers know as Winter Leaf Drop (WLD), which is what happens to the trees during storage in winter quarters.  With the appearance of fall and a decrease in temperatures, the trees are brought indoors to protect them from freezes and frost damage. 

 Unfortunately, the most common recommendation freely given for storing the trees indoors is as follows:
"Give the tree as much light as possible, keep the medium moist, but never over water.  Let the medium dry out more than in summer.  Hold the tree at temperatures around 41 - 50 F (5 - 10 C)."

  If you have followed this advice and have had no problems, you are lucky because most people who did so had problems.  The trees start to shed leaves, leaf after leaf drops, and in spring, after the last frosts, when the trees are placed outside again, many trees have few or no leaves remaining on the limbs, twigs and branches.  The cleavage is often between the leaf petiole  and the leaf blade, the petiole remaining on the tree. Often the dropped leaf shows no chlorotic patterns or any other discoloration.  Our first thought is that Winter Leaf Drop was influenced by low-light conditions during winter times. But even with extra illumination Winter Leaf Drop continued.  Often, after bright, sunny mid winter days, more leaves are shed than after longer periods of less bright light.  So we tried to find out what might be the cause of Winter Leaf Drop.  We chose five lemon seedling trees, all about one foot high.  The seedling trees were placed in different locations with different conditions:

 1. The first seedling tree was placed in a cool and bright location at a south facing window, at temperatures around 43 -50 F (6-10 C).
2.The second seedling tree was placed in the same room, but at a north facing window.
3. For the third tree, we chose a temperate room with temperatures around 59 F (15 C).
4. The fourth tree was placed at the same temperatures but on a south facing window.
5. The last plant was placed in a warm room of 70 F (21 C) at a south facing window with extra illumination.

All trees were irrigated as needed, just to keep the root ball moist, but not wet and not allowed to dry out.  Only #5 was irrigated more regularly and fed evenly.  After winter we found that #1 shed nearly all its leaves. #2 dropped some leaves only, and the others had only lost some (fewer than five) or no leaves.  We found light may NOT be the factor causing WLD, so we thought about temperature. After a long discussion with citrus experts in Florida and Israel, it was found that temperature will cause WLD. The temperature tables from the book Biology of Citrus show that citrus stops root growth and root function if the soil temperature drops below 54.5 F (12.5 C).  Leaf activity will be reduced if the temperatures drops below 64 F (18 C).  Leaf activity means the full process of water evaporation for leaf surface cooling, energy transformation (photosynthesis) and starch reduction for building amino acids and other compounds for forcing plant growth and cell development.  Citrus controls its leaf temperature by evaporating water from the leaf blade.  This reduces the temperature even during hot periods and will maintain the leaf temperature at the optimum levels between 77 F (25 C) and 95 F (35 C).  But even on cold days the sunlight can heat up the leaf surface quite quickly to levels beyond the critical temperature of 54.5 F (12.5 C).  Photosynthesis itself works better in cooler conditions with high light radiation than in the warmer periods of the day, so most of the photosynthetic starch production is done in the morning before noon and less water is evaporated than during the afternoon.  Optimum leaf temperature for photosynthetic activity for most plants ranges from 50 F (10 C) up to 90 F (32 C). Photosynthesis itself  needs carbon dioxide, light and water to transform the carbon dioxide into starch and oxygen. During the night the starch will be oxidized to provide energy needed for plant growth and development. The whole process is called breathing. Water and nutrients for the breathing process must be taken up by the roots.  Oxygen and carbon dioxide will be delivered from the air around the plant, taken up by the leaf surface (and to some extent by other green parts of the plant) so leaf and root activity must run in a balance to provide the best plant performance for growth, flowering and fruit development.  If a citrus tree is stored at temperatures below 54 F (12 C) but gathers enough light for photosynthesis, this balance is broken.  The leaf activity requires water, which the roots cannot deliver.  The tree stops evaporation and water will be unavailable for cooling the leaf surface on bright days, so the tree reduces active leaf area by leaf abscission.  This seems to be the best theory about what causes WLD.

Partial or complete defoliation was never critical if the root ball was kept  a little more on the dry side, but if it was too wet, a quick root decline developed even if Poncirus trifoliata was used as a root stock.  Most of the trees recovered quite will in spring (if the roots stayed healthy and a heavy bloom was set).  But in recovering the whole canopy, often the trees used up much of their starch reserves in the stock, which did not fully refill during the short summer times.  After some years, many trees suffered, growth was stopped and the trees died because all of the starch had been depleted.  So what to do about WLD? Irrigation during wintertime seems to be a recommended practice to slow down WLD. Irrigation with warm water 77-90 F (25-32 C) supports the root function, even the water uptake, so WLD will slow down.  Irrigation reduces the plant stress during cold winter time and is therefore recommended.

 Keeping the trees in a room with high humidity seems also to slow down WLD but cannot prevent it.  Also a place more in the shade, to minimize  leaf activity, slows down WLD. Keeping the root temperature below 64 F (18 C) but at or above 59 F (15 C) seems to work best for stopping WLD.  The plant functions are minimized, but water and nutrient uptake for leaf activity is high enough to support the breathing process and leaf surface cooling by water evaporation.  If WLD persist, force the root temperature higher, around 70 F (21 C) this should stop leaf drop.  Sometimes during the winter, fruits dry out on the tree and drop if the tree is stressed too much.  So for fruit development and fruit maturity, higher temperatures and good leaf activity should be maintained.  Irrigation with a nutrient solution should be done even in winter.

 Hope this helps - Millet

Del Monte's product label claims that their 64-ounce container has 10 grapefruit, but our citrus test revealed only four would fit
 Del Monte makes the labeling claim that there are 10 grapefruit in its 64-ounce container of Sun Fresh Red Grapefruit. There is one problem, though: The 10 grapefruit claim is misleading — at best. In fact, if we were to put it on an accuracy scale of 1 to 10, we’d have to give it a 4.

TINA.org took a trip to the store this week in an effort to follow up on a tip about the issue from a reader. We checked out with the 64-ounce Del Monte container and 10 grapefruit.
 
Back at the office, we emptied out the contents of the jar and got to work peeling and segmenting the individual grapefruit, which we then dropped into the empty Del Monte container. After packing down the flesh of the fourth fruit, we could add no more. Six unpeeled grapefruit stood idly by.

The results of our citrus test closely mirrored those of a reader who said the Del Monte container could only hold five grapefruit when she put it to the test.

“Stating with emphasis and even highlighting the ‘Contains 10 Grapefruit!’ definitely seems to me to be false and misleading,” the reader wrote in an email. “I should have been getting one jar free with each one that I purchased.”
 
 While the pieces of grapefruit we deposited into the empty container were less meaty (but larger) than the “dismembraned” Del Monte pieces we took out, the original Del Monte jar held at least a couple cups of water with the grapefruit pieces. So the area gained by the larger “membraned” slices we put in was in effect offset by the removal of the liquid.

The reader said she bought Del Monte because she considered 10 grapefruit for the cost a “fair price.” Indeed, at the Connecticut grocery store where we made our purchases, the big container went for $7.99 while the loose grapefruit cost $1 each. Presumably, that’s a savings of a couple bucks — a nice markdown for one item on a grocery list.

But employ our citrus test and the savings turn into a loss.

http://www.dailycommercial.com/news/article_51d79fa0-f571-5169-9f83-53debc34be5e.html

Millet

Spinach has some defensins that provide resistance to the bacteria that causes citrus greening. What has been found is if genes that are in spinach is put into citrus we have citrus trees that are resistant to citrus greening. This could be the  best hope of defeating citrus greening which threatens citrus in Texas, Arizona, California and Florida.No other short term solution has been found. Every researcher in the world familiar with the disease h.as indicated that the ultimate solution will be bio-technology. Southern Gardens Citrus Growers, a major grower and supplier to many citrus juice labels including Tropicana, was one of the first growers with greening infected trees in Florida. It has since lost over 800,000 trees – a quarter of its groves. Citrus Greening the biggest challenge our industry faces right now. Citrus greening is in all 32 commercial citrus-producing counties in Florida. Before citrus greening, Florida was producing 242 million boxes or oranges. The most recent count this fall was 108 million boxes. The devastation has yet to bottom out since it takes as long as three years for the bacteria to kill a tree. In an unprecedented collaboration between the federal government, industry and researchers, work is happening on many fronts to limit the damage. Growers are watching hopefully as new trees infused with the spinach gene are growing in a government-controlled experiment. So far, the newly planted trees are thriving.
What we’re getting now with the latest work is true resistance. The trees don’t become infected at all with the bacteria. Then it has to pass the most important test of all. Will consumers be willing to buy orange juice squeezed from oranges containing a spinach gene?
Hawaii’s papaya crop was saved starting in 1998 when the plant was genetically modified to resist the domestic Ringspot virus which had been devastating the island’s crop.
Millet

https://www.youtube.com/watch?v=fnLEao4HmPI&feature=youtu.be

Millet

http://abc30.com/news/asian-citrus-psyllids-found-in-grove-near-exeter/384654/
Millet

To  combat pests like the Asian citrus psyllid, exotic fruit fly and glassy-winged sharpshooter that threaten the state's food supply, the California Department of Food and Agriculture is weighing a new plan that some organic farmers say doesn't do enough to prevent their crops from being ruined by pesticides.

The proposal would streamline the state's response to invasive insects by reducing paperwork and allowing the agency to quickly respond to an outbreak when it orders quarantines, sets traps or, more controversially, sprays pesticides. Under a worst-case scenario for farmers, mandatory pesticide spraying in or near organic farms would cost growers the typical 15% to 20% premium they can charge over regular produce.

The plan "lacks adequate consideration of organic agriculture and fails to properly assess the potential impacts on California's organic farmers," said Kelly Damewood, policy director for California Certified Organic Farmers, a certification agency, trade association and foundation representing organic operations throughout North America, including 2,300 members in California. In a letter submitted to the state Friday, Damewood said the proposal failed to detail the effect on organic farms if synthetic pesticides are applied.

To be certified organic, fruit, vegetables and meat must be grown or raised without synthetic pesticides, growth hormones, antibiotics, genetic engineering or chemical fertilizers.


The state, which released the plan in August for public comment, said it would first consider alternatives such as traps or the release of sterile insects. If an emergency does require spraying, the state would consider weather and wind patterns to reduce the risk of pesticide drift on organic farms.

Other potential controversies include risks to human health as a result of pesticide exposure and the effect of pesticides — namely controversial insecticides called neonicotinoids — on pollinating honeybees.

Steve Lyle, a spokesman for the California Department of Food and Agriculture, said the proposal doesn't give his agency new authorities. Instead, it lays out the environmental impact of all known pest threats and treatment programs for the state's $43-billion agriculture industry in advance so that the agency doesn't have to file emergency reports under the California Environmental Quality Act.

"We have the authority to take the necessary steps to protect our food supply and we've had it for years," Lyle said.

The report comes amid lingering anxiety within California's $2-billion citrus industry over huanglongbing, also known as citrus greening. The disease, which leaves fruit bitter and misshapen, has already inflicted $1.3 billion worth of damage on Florida's citrus industry.

There is no known cure for the disease, which is being spread by tiny insects called the Asian citrus psyllid. Although the disease hasn't taken root in California, the invasive psyllids appear to be showing up in more places in the Golden State. Quarantines restricting the movement of citrus trees have been issued in all or some of 14 counties, including Los Angeles, Orange and Ventura.

Agricultural agencies in Florida and California have tried to contain the pest by using a combination of insecticides and predator insects — in this case, Pakistani "vampire" wasps that attack the psyllids by sucking out their blood.

Tim Schubert, a senior plant pathologist for the Florida Department of Agriculture and Consumer Services, said the wasps are preferable over spraying because they don't harm organic growers and don't raise as much public alarm. Huanglongbing is also so advanced in Florida that spraying would be impractical, he added.

"That's a delicate thing to do," Schubert said of mandatory spraying. "We've had some fruit fly spraying which was met with considerable public outcry. We dread the day we might have to resort to that." - Millet

A recent publishing in the American Journal of Clinical Nutrition, researchers reveals that women who consume foods containing flavonols and flavanones experience a significant decrease in the risk of developing epithelial ovarian cancer, which is the fifth-leading cause of cancer death among women. (2,3)

Over the course of three decades, a team of researchers studied the dietary habits of 171,940 women between the ages of 25 and 55. They discovered that people who consumed food or drinks high in favonols (found in tea, red wine, apples, and grapes) and flavanones (found in citrus fruit and juices) were less likely to develop the disease. (1,2,3)

Results show that those who consumed high amounts of flavonol and flavanone had a lower risk of ovarian cancer.
Professor Aedin Cassidy, the study’s leader says, “This is the first large-scale study looking into whether habitual intake of different flavonoids can reduce the risk of epithelial ovarian cancer. We found that women who consumed foods high in two sub-groups of powerful substances called flavonoids — flavonols and flavanones — had a significantly lower risk of developing epithelial ovarian cancer.” (1,2)

The main food sources that were found repeatedly among the participants include black tea, onions, apples, citrus fruit and juices. Cassidy says, “In particular, just a couple cups of black tea everyday was associated with a 31% reduction in risk.” (1,2,3)

During the 16 to 22 year follow-up, the researchers found that there were a total of 723 cases of medically confirmed ovarian cancer. The team concluded that “higher intakes of flavonols and flavanones as well as black tea consumption may be associated with lower risk of ovarian cancer,” but they add that additional studies are needed to confirm their results further.

Millet

Chiquita Banana Brands International Inc agreed on Monday to a $682 million takeover by Brazilian Orange juice maker Grupo Cutrale.
The acquisition is a victory for Brazilian orange juice mega baron Jose Luis Cutrale, to add Chiquita to his tropical fruit business. Jose Luis Cutrale, a Brazilian is one of the largest Orange Juice manufacturers in the world. - Millet

 A research team at the University of California, Riverside has found a new tool that targets the Asian Citrus Psyllid's (ACP’s) olfactory system, and they’ve have identified a suite of odorants (odor molecules) that the insect detects. Some of these odorants can modify the behavior of ACP and may lead to the development of tools to tackle its spread. The ACP olfactory system is sensitive to a variety of odorants released by citrus plants. This presents an opportunity to develop attractants and repellents using odors. The ACP detects citrus-plant odors using tiny sensors on its antennae. The Universities lab performed a large-scale analysis of numerous citrus-emitted odors and identified the ones that strongly activate the neurons on the ACP antennae. Then, using a blend of activating odorants, the researchers developed an efficient attractant that could lure the ACP to sticky traps. This odor-based insect lure could be of use to growers in California and other parts of the world where ACP invasion is occurring.

The blend of odors the team of researchers identified consisted of myrcene, ethyl butyrate and p-cymene — odors found in nature. To test whether this blend was indeed effective as an attractant, the team performed field trials on citrus trees in a residential neighborhood in El Monte, Calif. They found that the odor-based traps caught nearly 230 percent more ACPs than conventional traps placed on the same trees. What’s particularly encouraging is that these three chemicals are affordable, useful in small quantities, and safe for human handling. They could be developed into monitoring and surveillance tools. Similar approaches can be taken to develop control strategies using odors for other insect pests of crops as well. The study also reports identification of odors that block the ACP olfactory system from detecting citrus odors and have potential for development into repellents. -Millet

Primarily due to the citrus greening disease, Florida orange production has nosedived from 242 million boxes of citrus in 2003-04 to a projected 108 million boxes this season. But grove care taking costs over that span have more than doubled to more than $2,000 per acre, also mostly because of greening. - Millet

http://www.wwltv.com/story/news/local/2014/10/21/inspectors-check-for-citrus-disease-in-plaquemines/17689491/

Millet

 

County agricultural officials are reporting the detection of more Asian citrus psyllids in San Luis Obispo.
The pest is of concern because it can spread the disease Huanglongbing, also called citrus greening disease. It can be fatal to all kinds of citrus trees. The insects were found in northern San Luis Obispo near the Veterans Hall, where the insect was first detected in August. Three adult psyllids were found on a single property. The San Luis Obispo County Department of Agriculture has responded with control efforts in the immediate area of the detection, which includes trapping.
“The discovery of additional psyllids is of concern to local citrus producers, residents and regulatory officials,” said Martin Settevendemie, county agricultural commissioner. “The focus of our work will be to continue to monitor for the presence of psyllids through intensive trapping, visual inspection of citrus plants and suppressive treatments to keep this pest out of local commercial citrus orchards and residential landscapes.” A single tree infected with citrus greening disease was found in a Los Angeles County backyard in 2012. Since then, no additional detections of the disease have been made. The disease does not affect human or animal health and citrus fruit remains safe for consumption.

Millet