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Fire Information for Avocado and Citrus Growers
The following is a compendium of blogs for growers that arose out of the recent fire damage in the Santa Barbara/Ventura area:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26670
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=28711
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26510
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26353
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26095
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=25899
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=25885
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=24639
For tree growers who have further questions about how to treat fire-affected trees, please don't hesitate to contact your local Cooperative Extension office.
fire 1
Avocado Orchards in Fire Season
The very fact that avocados can be grown in hard to get to places means that the trees are also in areas that are subject to wildfire damage. Recently several hundred acres of avocado burned in the foothills. The fire was fanned by high winds and low humidity.
Every year there are avocado trees that burn, either through careless attention to early morning fires that pickers build, wildfires or car accidents. A grower needs to be patient and observant to bring the trees back into production.
Although injury to foliage and young growth is visible within a few days of the fire, the full extent of the damage may not be known for several months or possibly the next growing season. In the case of severe injury, die-back may continue to occur for several months after the fire. New growth that occurs after the fire may suddenly collapse the following year when the growth is tested by Santa Ana conditions.
The important rule to follow after a fire is to do nothing - don't prune, don't fertilize and maybe don't water. Or rather, water very carefully. Dry winds may have sucked the water out of the ground and may need to be replenished. The fire may have burned the irrigation lines and need to be replaced.
In the meantime, if the tree has been defoliated by the fire, it has lost its ability to transpire water. Watering a tree with no leaves will set up those conditions that are conducive to root rot. Until the tree begins to leaf out, watch soil moisture to decide how much water the trees are pulling out of the soil. The emitters should be capped or plugged on some leafless trees. Then as the tree puts on new growth, shallow, infrequent irrigations should start. This may mean replacing the 10 gph microsprinkler with a 1 gph dripper if only a portion of the orchard has been burned and the rest of the trees need their usual amounts and frequency of water.
The avocado has a tremendous ability to come back from fire and frost damage. However, the tree will tell you where it is coming back. It will start pushing growth where the tree is still healthy. It may take 3 to 6 months for this growth to occur.
Delay pruning until the tree clearly shows where it is going to regrow. By waiting, you save the expense of having to return sometime later to remove more wood and also will be able to save the maximum about of tree.
An activity the grower can perform is whitewashing. The defoliated tree can be further damaged by sunburn after it has lost its protective cover of leaves. The upper surface of horizontal limbs and the south sides of exposed trunks are the most affected. The whitewash can delay the appearance of new growth, but it does not affect total growth. There is usually no value in applying the whitewash to small limbs.
There are various commercial whitewashes on the market. The easiest to prepare is the cheapest white latex paint on the market mixed with water to the extent that it will go through a sprayer.
Avocado trees have a great ability to recover after fire damage. Even trees killed below the bud union will frequently develop into good trees if they are rebudded and given good care. Trees which do not put out vigorous sprouts should be removed. Interplanting avocados would rarely be advisable because of their rapid recovery.
Fire Information:
http://ceventura.ucanr.edu/Agricultural_Threats/Fire_Information/
IMG 2031
Soil Health Websites
A recent website just posted hopes to make research papers available to the general public. Many times these papers are locked away in archives or libraries and are hard to access. This website wants to change that. It is sponsored by various group0s, including USDA, University of Missouri, industry, Resource Conservative Districts and other entitites. It's a small data base at this point, but hopes to build over time. check it out:
http://soilhealthinstitute.org/about-us/
There's a lot of distracting stuff at the site, but the guts are at
http://www.soilhealthinstituteresearch.org/Home/Search
Other good ag websites are the USDA's National Ag Library:
USDA's Agricola
https://agricola-nal-usda-gov.ezproxy.lib.vt.edu/
USDA's ATTRA which is loaded with basic and detailed farming information:
USDA's Farming Information Center
https://www.nal.usda.gov/afsic
It's a new year, READ ON!!!!
soil
Irrigation Information Sources
In a recent meeting the topic of where to go for irrigation information came up. Well there's no substitute for attending a class in irrigation, such as offered at Cal Poly SLO (http://www.itrc.org/classes/iseclass.htm ,
but here's some written sources to get you started thinking.
http://ciwr.ucanr.edu/california_drought_expertise/droughttips/
http://www.salinitymanagement.org/Salinity%20Management%20Guide/ei/ei_1.html
http://www.avocadosource.com/tools/IrrigationCalculator.asp
http://lawr.ucdavis.edu/cooperative-extension/irrigation/manuals
http://lawr.ucdavis.edu/cooperative-extension/irrigation/drought-tips
http://biomet.ucdavis.edu/index.php/evapotranspiration-mainmenu-32
http://www.fresnostate.edu/jcast/cit/goods/
http://edis.ifas.ufl.edu/topic_citrus_irrigation
http://edis.ifas.ufl.edu/results.html?q=irrigation&x=0&y=0#gsc.tab=0&gsc.q=irrigation&gsc.page=1
X
irrigATING CITRUS
Where to Look for Infornation about Avocado Varieties
There are something like 1,000 named varieties of avocado. Big, small, green, black, purple, round, pear-shaped, winter, summer, fall harvest, anise smelling leaves, all kinds of distinguishing features. A homeowner once called to ask about the ‘San Marcos' variety of avocado and we viewed images of this tree and fruit and finally figures out it was a ‘Bacon' that was planted on San Marcos Pass and had adopted the new name because they didn't know what to call the avocado tree in the backyard. So there are a lot of trees that are misnamed for known varieties.
If you want to find out the name of an unknown tree in your backyard, there is a convenient online source of information at Avocado Information at UC Riverside. There is an online list with photos of avocado varieties at:
http://ucavo.ucr.edu/avocadovarieties/VarietyFrame.html#Anchor-47857
And a variety database you can use to search by name at:
http://www.ucavo.ucr.edu/cgi-bin/Panorama.cgi?AvocadoDB~form~Search
There's also a list of unreleased varieties at:
http://ucavo.ucr.edu/avocadovarieties/UnreleasedVarieties.html
One of the best sources of variety information is the CA Avocado Society Yearbook where most varieties were listed for registration. Some of the descriptions are online, but in many cases it's necessary to go to the original paperback version
http://www.avocadosource.com/CAS_Yearbooks/CAS_Yearbooks.htm
Yearbooks can be found at many UCCE offices in Southern California, UC Riverside and Davis libraries, many Southern CA public libraries and from interlibrary loan.
avocado fruit
