The talk of drought and water restrictions in the State has created a time for serious decisions. What can be done with avocado citrus trees that have been invested with time and money when there are allocations of water? Although this article is addressed to subtropicals specifically, the guidelines are generally applicable to all fruit trees.
Irrigation systems and scheduling
One of the surest, although not necessarily the cheapest, ways of managing with a decreased amount of water is to improve its application and scheduling. Insure that equipment is working properly, that nozzles are not plugged or worn, that pressures in the irrigation blocks are uniform, that leaks are repaired, and that no runoff or deep percolation are occurring. Many Resource Conservation Districts have Mobile Labs that can help make a system evaluation.
In the Ventura area, oranges use about 30 inches of water per year, however , the monthly amount varies with weather. Applying water in the amounts and at times for optimum production can be improved by using tensiometers. A gauge reading near 40 centibars has been recommended for the one foot tensiometer. The three foot tensiometer can be used to determine the amount of moisture stored in the lower horizon and to determine whether the irrigation was effective, whether the irrigation water infiltrated down to that depth.
Whatever reading is used there is no substitute for observation of the trees themselves and the soil.. Use a soil sampler or shovel to verify the depth of water applied. If time clocks are being used, turn them off or at least adjust them frequently enough to accommodate changing weather patterns. Use of CIMIS weather data can aid in correcting schedules to changing weather.
If water applications need to be curtailed, there will be a decline in yield and fruit size. Applying something less than about 75% of tree requirement will give reduced yields not only for this year, but will lead to dieback and low yields for 3 -4 years after. Abandoning the trees altogether will also yield little or no crop and dieback, but the trees will often return to normal yields in 3 - 5 years. If little water is available, it may be best for commercial operators to reduce the number of trees irrigated to those that can receive 85% of their water requirement and abandon the rest, hoping for more water in future years.
Since it is the leaves that are the site of water loss , the best way to reduce water loss is to reduce the amount of leaves present. This is the ideal time to thin an orchard, get rid of those trees that are shading each other and reducing the per tree yield of fruit. This is a good time to topwork trees to better varieties, since the smaller trees will use less water. A good weed management program will reduce competition for water, and mulching the wetted area of the sprinkler will reduce evaporative loss from the soil surface. Once the leaf area is reduced, it is necessary to adjust the irrigations to reflect the decreased need for water.
This is an opportunity to identify the least productive trees in an orchard and cut of water to them. Trees with root rot or frost damage; trees growing on limy/iron chlorosis sites. Trees growing on ridges that receive the full force of the wind and have a lower yield per gallon of water should be considered first. Trees growing on the perimeter of an orchard also will transpire more water for a given amount of fruit. If all trees in the orchard look good, then these perimeter trees should be targets for saving water. If production records have been kept for different blocks of trees, it might be possible to identify low yielding areas that could be sacrificed.
This is an opportunity , as well. Many growers have kept poor producing parts of groves going because it is an emotional issue to cut up a tree. Seize the day and take advantage of the situation.
For more, check out the powerpoint
In a mandarin orchard today, I saw what appeared to be sun burn damage. The bark was missing on the top, south facing branches. It was old damage and was healing over along the edges. I mentioned it to the grower who told me it was roof rat damage. Several years prior when we had had a long dry winter, the rats had come out of the hills and were eating his fruit, as well as feeding on the cambium. I've seen this damage in trees near the edges of wild country, as well as along stream and river beds. At one orchard in Santa Paula, the feeding had actually spread Phytophthora in the canopy of lemon trees. For control measures go to:
- Author: Jodi Azulai, UC Statewide IPM Program
Imagine a pesticide sprayer smart enough to hit trees and turn off between them. What would that mean for your wallet? What would it mean for the rivers and streams near your orchard? View On Target, a video that shows how smart sprayer technology is helping farmers manage orchard pests with clever results:
- Substantially reduced pesticide use and cost
- Less pesticide movement to rivers and streams
- Full tree coverage
- Same efficacy as conventional sprayers
- Ease of use
- Valuable application data
Walt Bentley, retired UC IPM Advisor, narrates this video showing a smart sprayer in action.
Smart sprayer technology is based on the use of high frequency sound waves. An onboard computer directs sound waves toward trees. When sound waves are returned, a target is detected and the computer triggers nozzles to spray. When sound waves are not returned, a gap is identified, prompting the program to turn off nozzles.
Find the video on the UC IPM Mitigation Pesticide Hazards page at http://www.ipm.ucdavis.edu/mitigation/index.html. Scroll down to the second bullet under “Before application.” Remember this page the next time you plan a pesticide application. It will help you consider practices that minimize environmental and efficacy problems.
A new publication, "How to Attract and Maintain Pollinators in Your Garden," (Publication 8498) has been added UC Agriculture and Natural Resources (ANR) catalog. The document is a collaboration of UC experts which includes an entomologist, laboratory assistants, landscape designer, photographer, and pomology expert.
Pollination is crucial to the survival of much of our ecosystems and maintaining viable environments for them to thrive provides not only benefits to personal outdoor space, but adds to the well being of the community at large.
This publication focuses on ways to make your garden and outdoor environment, including avocado orchards more attractive to pollinators by identifying pollinators and the plants and landscaping practices that appeal to them.
ANR Publication 8498 is free of charge and available as a downloadable PDF.
You can download this publication here.
UC Riverside and the Citrus Research Board partner to provide:
UC Riverside Citrus Day for Professional Industry members
Thursday, February 20, 2014
8 a.m. to 3:00 p.m.
UCR Agricultural Operations, Riverside, California
For information: (951) 827-5906
Please join us for the 3rd Annual Citrus field day designed for citrus growers and citrus industry representatives. Pending approval, we will be offering 2.5 hours of California Continuing Education
Credit for Pest Control Advisers (PCA).
Presentations, field tours and topics of interest:
Pesticide safety – Vince Samons
Update on ACP and HLB in California – Joseph Morse
Phytophthora diseases of citrus – Jim Adaskaveg
Lemon Varieties for the Desert –Glenn Wright
Understanding factors that influence the eating experience in citrus – David Obenland and Mary Lu Arpaia
Citrus Variety Collection tours of new cultivars and “unforbidden” fruits – Tracy Kahn, David Karp, Tom Shea, and Robert Krueger
Update on Citrus Rootstock Field Demonstration – Mikeal Roose
Barbeque Lunch included.
Registration: $18. Deadline: February 14, 2014. There will be no walk-in registrations. We will email directions and updates to all who have registered.
Space is limited so please register early.
Please register online at
To make a tax-deductible contribution to the
Citrus Variety Collection Endowment fund or the Citrus Research Center & Agricultural Experiment Station support fund go to the following link and select College of Natural and Agricultural Sciences then select the specific fund: