- Author: Ben Faber
There have been so many calls recently with the same problem, thinning canopy with dieback. Thiscan be caused by several problems, but the most common this time of year is lack of good water management over the year, accentuated by lack of rain and salt damage. The rain will often leach salts accumulated from the root zone over these many years of water from only irrigation. I thought as everyone else did that we would be having some gushers in S. California and some of these problems would be relieved. With rain, the cankers from black streak, bacterial canker and Botryosphaeria canker (Dothiorella) staining are washed away, and often times, so are the tree's problems. Well that hasn't happened. Or rather the rain hasn't happened to resolve this problem - Botryosphaeria or Bot Rot.
This problem has been ongoing and growers are still calling in about avocados with thinning canopies, fruit drop and sunburn and leaf death. Coastal avocados are always difficult to irrigate. Mild weather followed by dry windy conditions means growers have to scramble to get water on. If the trees are on some sort of calendar schedule, it usually means the trees get stressed. If trees are on a slope where pressure is not properly regulated, some of the trees are going to get stressed. If emitter clogging is not addressed, then more trees get stressed. And lack of rains to leach salts from the root zone, and more trees are stressed.
This stress sets up the trees for disease and a very common one in an avocado orchard that is filled with lots of leaves where decay fungi are working is stem and leaf blight. The disease causes defoliation and exposed fruit sun burn and drop. In an orchard, it's possible to see healthy trees and sick ones at the same time. This may be due to the differences in soil type from tree to tree or the fruit load on trees - more fruit, more stress. Looking out over the orchard there may be a polka dot of sick trees. And it might all happen at once in a week or gradually.
So, this is a problem that is out there, if the irrigation issue is corrected, the trees usually recover. It might require white washing and pruning out dead tissue. If it is a young tree under two years, it might actually kill the little tree, but the disease is not usually fatal, just loosing the fruit.
This is a disease that goes to many different tree species - redwoods, eucalyptus, pine, Brazilian pepper, CITRUS. The cause is the same, water or salinity stress. To read more about this disease, go to:
http://www.ipm.ucdavis.edu/PMG/r8101311.html
Thinning canopy, dieback and shriveled fruit in avocado and dieback and gumming in citrus
- Author: Ben Faber
Lots of seeds; thick, coarse skin; not big, not small; thorns; sour; but fragrant, cold tolerant and selling for good prices. A cross between one of the original citrus parents – papeda – and a mandarin. It's got some pretty ancestral properties with something of a lemony flavor and a grapefruit odor. Yuzu is a citrus fruit esteemed by Japanese and Korean chefs just for the qualities of the juice and peel. At this point it cannot be imported fresh, so must be grown in California if it is used as a fresh ingredient. And prices at a recent farmers market made me shake my head at what was being charged. I would hate to think what would happen to prices if suddenly we had 500 acres of the fruit.
For more on yuzu, check out the UC Citrus Variety Collection at:
http://www.citrusvariety.ucr.edu/citrus/yuzu1.html
Check out the seeds in this fruit
And the productivity
- Author: Ben Faber
It seems the world is attacked on all sides, including the iconic citrus and avocado industries in California. Aside from the other agricultural issues all growers have of water, labor, costs, weather, family, you name it, citrus and avocado growers have particular problems. There is Asian Citrus Psyllid/Huanglongbing for citrus and the Shot Hole Borers for Avocado. The latter is a beast that is going to lay waste to many other tree species besides avocado, like sycamore, coast live oak, native maple and many other tree species.
Citrus and avocado are still strong industries in California and will remain so as solutions to these pest invasions are dealt with. But we are coming up to the time when maybe other tree crops should be considered. These alternative tree crops come with new promise, but they also come with problems. You have to figure out how to market them. The California industry knows what to do with an avocado and a grower knows where to go with a ‘Gold Nugget' mandarin, but what do you do with a longan or cherimoya. You figure out how to market it, through direct marketing at farmers markets or the internet, some specialty marketer like Frieda's Finest or Melissa's or your regular packer who has taken an interest in your product.
I've spoken with growers who say they have grown such and such for four generations and they are not adjusted physically or psychologically to grow anything else. Well, it is good to stick with what you know best and refine it for current conditions, but it's also good to keep options open. Stick to what is best for your situation and support the studies needed to make citrus and avocado strong industries, but also think about maybe something else.
Here's links to tree crops that do well in Southern California and for that matter can be adjusted to much of California. Just watch out, it gets cold north of the Grapevine and San Luis Obispo and options are more limited with subtropicals, but think deciduous.
Subtropicals
http://ceventura.ucanr.edu/Com_Ag/Subtropical/Fruit_and_Nut_Varieties/Citrus_and_Other_Subtropicals/
Deciduous
http://ceventura.ucanr.edu/Com_Ag/Subtropical/Fruit_and_Nut_Varieties/Deciduous/
- Author: Ben Faber
Pomegranate (Punica granatum) is a specialty crop now grown on more than 10,000 acres in California. Pomegranate production has increased for both fresh market and juice in the last several years, and with this increase, random internally rotted fruit has become more noticed. The outside of the fruit looks perfectly fine, but internally the fruit is rotted and the arils (the flesh covered seeds that are eaten and juiced) are black. Pretty disgusting. Some fruit recently has shown up at harvest and the grower was unaware of the problem until the fruit was opened by a customer. The only difference between good fruit and affected fruit is that the blackhearted fruit is a bit lighter in weight. The absence of external symptoms makes the diagnosis of the disease very difficult, and consumers encountering the disease may change their perception of the pomegranate's many health benefits.
Initially, it was thought that the disease was caused by various fungi that can decay the arils. However work by Themis Michailides from UC Kearney REC has shown that after inoculation of pomegranate flowers and developing fruit that the main cause of black heart is Alternaria spp. These fungi are very abundant in nature and cause diseases in a multitude of crops. Another fungus that is also isolated from pomegranate with black heart is Aspergillus niger. However, the decay caused by A. niger is softer than that caused by Alternaria and results in exuded juice. In addition, another major difference between black heart caused by Alternaria spp. and that caused by Aspergillus is that the latter decays both arils and rind of fruit and frequently symptoms reach the outer surface of fruit, which helps in the diagnosis of the disease. Inoculations with Alternaria spp. reproduce the typical symptoms of black heart (internal decay of the arils without any external symptoms).
Inoculations periodically with Alternaria spp. showed that most of the infections occur at bloom time and that spores of the fungus that are introduced into the fruit (puncturing from thorns, hemipteran feeding like aphids and stink bugs, or cracking) can result in black heart. The current research focuses on the identification of the various species of Alternaria that cause black heart, the understanding of the infection process, and the development of procedures to manage the disease.
Alternaria alternata and related species commonly occur on plant surfaces and in dying or dead tissues of plants. The pathogens overwinter on plant debris in or on the soil and in mummified fruit. The spores are airborne and can be carried to the flowers with soil dust. Infections may also start from insect and bird punctures on fruit. Research in the San Joaquin Valley showed that the petal fall stage seems to be the most susceptible stage when most of the infection occurs. However, infection can occur throughout the long bloom and fruit development periods.
Estimated losses are usually less than 1% but can be up to 6%.
So how does a grower reduce black heart? Fungicide coverage has been a problem for bloom fungicides, but Michailides has shown some promising new materials. Good orchard management practices, such as dust control and sanitation (removal of old fruit and dead branches), may reduce the incidence of the disease. Infected, healthy-appearing fruit may be dropped to the ground by gently shaking the tree at the time of harvest. Avoid water stress and overwatering that may result in fruit cracking.
Thorough sorting and grading of pomegranates for discoloration and cracking can help avoid packing diseased fruit.
- Author: Ben Faber
Well it came again, the Citrus Tasting at Lindcove Research and Education Center in Lemon Grove near Exeter, close to Visalia and just down the road from Fresno and up from Tulare. They came, growers to see and taste new and old varieties. And then the next day, the general public with oooos and ahhhs to taste the range of flavors we call citrus. Big fruited pummelos and little fruited finger limes. Sweet, sour, not sweet, not sour, dull, and boing!. Growers came on Friday morning and the general public the following Saturday. It was crowded both days.
Citrus is wonderful, everyone knows, but it is also under dire threat of Huanglongbing and the potential destruction of this industry and the trees that are found in many backyards. So in a completely unscientific survey, I asked growers why they were there if their world was about to end. First of all, those who showed up were already optimistic about the future, so there was already a self-selection. But, growers felt like a solution would be found, science would find an answer. Driving across the Valley and through coastal counties like Ventura there are lots of new plantings......if there's water. But it's surprising how confident growers are about finding a solution. There are some hopeful signs out there like the new rootstock release from USDA of US-1516 which shows a lot of tolerance to the disease. Then there is the potential of disease tolerance in a citrus produced in Florida from a collaboration of Southern Gardens, USDA and a consortium of Universities. Yes, there is hope, but years are still needed to test and gear up for production for commercial applications.
So it was good to be around growers who have an enthusiasm for the future and looking for new planting varieites.
And they are both grapefruit, one is Melogold the one on right is Oro Blanco
Buddha's Hand citron
The Citrus Display at Lindcove Research and Extension Center, before the crowds