- Author: Chris M. Webb
The University of California has a learning management system (LMS), an online learning site open to everyone. Some of the courses are free, including one for citrus integrated pest management (IPM).
California Department of Pesticide Regulation (DPR) credits are available for some courses.
4-H child safety online can also be viewed through LMS. This course is part of the process to become a 4-H Volunteer Leader.
This is a relatively new site, and more classes will most likely be added in the future. Registration is easy. To find out more, or to sign up for a class follow this link.
- Author: Chris M. Webb
There is much community and grower support to stop the Asian Citrus Psyllid (ACP) from becoming established in Ventura County. While it has not yet been identified in our county, it is very close. An ACP was found recently in Van Nuys.
This is an extremely dangerous pest because it can carry the vector for the disease, Huanglongbing (HLB, also known as citrus greening), that destroys citrus trees, orchards and related industries in locations were ACP becomes established.
Invasive pests and disease, such as the ACP/HLB pest-disease complex negatively affect agricultural productivity, public health, natural resource biodiversity and our own backyards.
Thank you all for your support. Please contact our office if you would like hard copy outreach materials for yourself or for groups.
- Author: Chris M. Webb
The Asian Citrus Psyllid (ACP) continues its advance through Southern California. This is an extremely destructive pest. The disease it carries is capable of destroying citrus trees, orchards, and related industries.
An ACP Task Force has been formed in Ventura County. Top priority is to reduce the spread of the psyllid, which in turn will reduce the spread of disease. Your help is needed to stop this pest. You can help in the following ways:
- Do not bring citrus trees, other plants, or fruit into the state from other counties, states, or countries.
- If you have citrus on your property, please check regularly (at least monthly) for signs of infestation. Details on what to look for can be found here.
- Encourage your friends, neighbors and relatives to do the same
- A suspected ACP infestation should be reported immediately to the CDFA hotline at 800.491.1899, or your county agricultural commissioner. The Ventura County Agricultural Commissioner can be reached at 805.933.2926
The Ventura County ACP-HLB task force will be conducting a workshop on February 25, 2010 designed for growers and pest-control advisors. More information about the workshop can be found here.
Our office has outreach materials available to help spread the word. Please contact us if you would like some.
Psyllid eggs and nymphs tucked into crevices and folds.
Asian Citrus Psyllid nymph
Asian Citrus Psyllid adult
- Author: Chris M. Webb
Today Ventura County Cooperative Extension Farm Advisor, Ben Faber shares some of his knowledge of citrus with us.
Citrus leaves appear wilted or flaccid during periods of low temperature. This is a natural protective response to freezing temperatures and does not mean the leaves have been frozen. Leaves will be firm and brittle and often curled when frozen. Leaves become flaccid after thawing, and if the injury is not too great, they gradually regain turgor and recover, leaving however, dark flecks on the leaves. Seriously frozen leaves collapse, dry out, and remain on the tree. Foliage form recent flushes are most susceptible to this damage. If twigs or wood have been seriously damaged, the frozen leaves may remain on the tree for several weeks. If the twigs and wood have not been damaged severely, the leaves are rapidly shed. Trees losing their leaves rapidly is often a good sign and is not, as many growers believe a sign of extensive damage.
Cold damage to the twigs appears as water soaking or discoloration. In older branches and trunks it appears as splitting or loosening of bark where the cambium has been killed. Bark may curl and dry with many small cracks. Dead patches of bark may occur in various locations on limbs and trunk. Sensitivity to frost is dependent upon many variables. In general, mandarins are the most cold hardy followed by sweet orange and grapefruit. Lemons are very frost sensitive with Eureka decidedly more sensitive than Lisbon. Limes are the least cold hardy. Healthy trees are more tolerant than stressed ones. The rootstock also imparts sensitivity onto the scion. Injury to the foliage and to young trees may be immediately recognizable but the true extent of the damage to larger branches, trunks, and rootstocks may not appear for on to four months following the freeze. No attempt should be made to prune or even assess damage from the frost until spring when new growth appears.
- Author: Chris M. Webb
Today Ventura County Cooperative Extension Farm Advisor, Ben Faber shares some of his knowledge of citrus with us.
The only treatment that should be done rapidly after a freeze is whitewashing. Often the most severe damage following a freeze results from sunburn of exposed twigs and branches after defoliation. Temperatures do not have to be extremely high to cause sunburn. A white latex paint that has been diluted with water so that it can be sprayed is the easiest way to whitewash. The whitewash needs to be white on the tree, so don’t add too much water.
Pruning should be carried out to prevent secondary pathogens and wood decay organisms from slowing tree recovery. Again, however, there should be no rush to prune. Premature pruning, at the very least, may have to be repeated and, at the worst, it can slow tree rehabilitation. It should be remembered that when pruning, all cuts should be made into living wood. Try to cut flush with existing branches at crotches. Do not leave branchstubs or uneven surfaces. Tools should be disinfected in bleach or other fungicide before moving on to the next tree.
Irrigate carefully! Remember that when leaves are lost, obviously evaporation from leaves is greatly reduced, and, therefore the amount of water required is also greatly reduced. A frost-damaged tree will use the same amount of water as a much younger or smaller tree. Over irrigation will not result in rapid recovery. Instead, it may induce root damage and encourage growth of root rotting organisms. Irrigation should be less frequent, and smaller amounts of water should be applied until trees have regained their normal foliage development.
Fertilization of freeze-damaged trees should be carefully considered. There is no evidence to indicate that frozen trees respond to any special fertilizer that is supposed to stimulate growth. If trees are severely injured-with large limbs or even parts of the trunk killed-nitrogen fertilizer applications should be greatly reduced, until the structure and balance of the tree become re-established.
Trees should be watched for evidence of deficiencies of minor elements. Deficiencies of zinc, manganese, copper, and iron are most likely to develop. For citrus, these materials should be applied as sprays, and they should be used as often as symptoms are observed. Two or more applications may be required the first year.