In honor of #HealthySoilsWeek2020, our healthy team would like to share background and an update on our healthy soils project @Limoneira in Santa Paula. Our group of researchers and advocates at @VenturaCountyResources Conservation District @UC Cooperative Extension and @Community Environmental Council are studying the climate, water and soil impacts of @Agromin mulch and compost on a new lemon orchard.
Hoping for better days, instead of a field day this year, we hope you enjoy this video to learn more about this project. We are only about halfway through the project, so stay tuned for more results next year!
This project was funded through the Healthy Soils Project at the California Department of Food and Agriculture. CDFA's Healthy Soils Program includes 643 projects totaling more than $42.2 million in grants funds. These projects cover almost 60,000 acres and will sequester more than 112,000 metric tons of CO2e, which is equivalent to removing 24,250 cars from the road each year.
- Author: Pam Kan-Rice
A new study on the costs and returns of establishing and producing lemons in Ventura County has been released by UC Cooperative Extension in Southern California and UC Agricultural Issues Center, both part of UC Agriculture and Natural Resources.
“Coastal agriculture is always in transition and as strawberries and vegetables become less profitable due to markets and labor availability, lemons have returned as a potentially profitable alternative to those crops,” saidBen Faber, UC Cooperative Extension farm advisor for Ventura County and coauthor of the study.
California lemon acreage was at roughly 47,000 acres in 2018-19, of which Ventura County accounts for 31%, according to the 2019 Ventura County Crop Report. Ventura County was growing lemons on 14,407 acres in 2019.
“The profitability of lemon production depends on the price of land,” said Etaferahu Takele, UC Cooperative Extension farm management advisor for Southern California, another coauthor of the study. “If the price of land continues in its current trend, it could be prohibitive for new entrants to make a profit and limit further expansion of lemon production in the county.”
Their cost analysis describes production operations for Eureka lemons on macrophylla rootstock, which are planted at 155 trees per acre with an expected life span of 40 years.
The study includes a detailed summary of costs and returns and a profitability analysis of gross margin, economic profit and a break-even ranging analysis table, which shows profits over a range of prices and yields.
Input and reviews were provided by Ventura County farm advisor and grower cooperators. The authors describe the assumptions used to identify current costs for lemon establishment and production, material inputs, cash and non-cash overhead.
The new study, “2020 - Sample Costs to Establish and Produce Eureka Lemons in Ventura County,” can be downloaded for free from the UC Davis Department of Agricultural and Resource Economics website at http://coststudies.ucdavis.edu and the UCCE Riverside County Farm Management website at https://ucanr.edu/sites/Farm_Management/files/338947.pdf. Sample cost of production studies for many other commodities are also available on the websites.
For additional information or an explanation of the calculations used in the studies, refer to the section of the report titled “Assumptions” or contact Takele at (951) 683-6491 Ext. 243 email@example.com or Donald Stewart at the UC Agricultural Issues Center at (530) 752-4651, firstname.lastname@example.org.
For information about production of lemons in Ventura County, contact Faber at email@example.com.
Lemon Orchard - Edward Okun
The calls have come in. We've gone from cool to hot and Dry Root Rot of Lemon has struck, It's shocking how fast the trees go down.
Dry Root Rot has menaced growers in Ventura County for many years. In the ‘50's and ‘60's it seemed most prevalent on older orange trees. A few years after the wet winter of 1968-69, dry root rot became an increasing problem among citrus trees of all ages. At that time, most of the damaged trees were on sweet rootstock (susceptible to Phytophthora), and growing in fine-textured soils or soils with poor drainage. A few years after another wet winter/spring (of 1983), dry root rot again reared its ugly head, but this time predominately on young lemons.
The disease is caused by the fungus, Fusarium solani. This fungus is most likely present in all citrus soils in California. It is a weak pathogen in that by itself it will not attack a healthy tree. However, experiments conducted in the early 1980's by Dr. Gary Bender, showed that when seedlings were girdled, root invasion occurred. In the field, the fungus can infect trees once gophers have girdled the roots or crown. A Phytophthora infection will also predispose trees to Fusarium, as will asphyxiation. Therefore, the mere presence of the fungus in the orchard soil will not lead to the disease.
Fusarium is a soil borne fungus that invades the root system. Once infected, the entire root will turn reddish-purple to grayish-black. This is in contrast to a Phytophthora infection which, in many cases, will attack only the feeder roots, but when larger roots are infected, only the inner bark is decayed and it does not discolor the wood. In addition, when observing the cross section of a dry root rot infected trunk, a grayishbrown discoloration in the wood tissue can be observed.
Dry root rot is a root disease, but symptoms of the root decline are seen above ground. They are similar to any of the root and crown disorders such as Phytophthora root rot, oak root rot fungus (Armillaria) and gophers. The trees lack vigor, leaves begin to turn yellow and eventually drop (especially in hot weather) causing twig dieback. Finally, the foliage will become so sparse that one will be able to see through the canopy of the tree. A period of two to three years may pass from the time of invasion until noticeable wilt. Many times, the tree will collapse in the summer, after a period of prolonged heat. In the case of dry root rot, the collapse is so rapid that the tree dies with all the leaves still on the tree. When looking for symptoms of dry root rot, keep an eye out for symptoms of other maladies as well — Phytophthora, oak root rot fungus and gophers being the most prevalent.
As mentioned previously, in order for Fusarium to infect a tree, there must be a predisposing factor such as girdling from gopher feeding. However, since many trees collapse from dry root rot without any apparent predisposing factor, there are obviously other factors which we have yet to identify. Therefore, in 1998, a grower survey was developed, along with intensive soil and leaf sampling, to attempt to identify as many new predisposing factors as possible. They might be elements in the soil, either deficiencies or excesses, or specific cultural practices such as irrigation patterns or fertilizer practices. Twenty orchards were identified from which 20 soil and 20 leaf samples were taken in diseased areas and another 20 soil and 20 leaf samples were taken from adjacent healthy areas. The owners or managers of the properties were given a questionnaire to complete regarding a variety of cultural operations. The objective was to identify those factors that would correlate well to trees becoming infected with dry root rot.
Soil analysis - The following laboratory procedures were conducted to see if there was any correlation between the disease and either deficiencies or toxicities of these elements or
conditions: sodium, boron, salt level, pH and soil type (sand, loam, clay). For these elements or conditions, no correlation was found. It would appear that for our sampling sites, these conditions, whether favorable or not (toxic or deficient), did not play a major role in predisposing the tree to dry root rot.
Leaf analysis - The following elements were analyzed for their concentration within the leaf: nitrogen, potassium, phosphate, manganese, magnesium and zinc. Of these, three correlations were found. Zinc and manganese levels were substantially higher in diseased trees. The third correlation showed a potassium deficiency in diseased trees. However, we do not believe that dry root rot is caused by elevated levels of zinc or manganese, or by potassium deficiency, but rather are a result of the disease. Unfortunately, it seems that we have still not identified any elements in leaf analysis that truly correlates and points to a predisposing factor for disease development.
Control Measures – What Works and What Does Not
Early experiments conducted by Menge, Ohr and Sakovich showed that the following circumstances or operations do not influence the incidence of this disease: fungicidal treatments, wounding the tap root at time of planting, sandy versus clay textured soils, spring versus fall planting and soil mounding.
- In choosing your nursery tree, the choice of rootstock is not important in that, as far as we know, all rootstocks are susceptible to this disease. However, since Phytophthora is a major component in dry root rot development, choosing a rootstock like sweet orange would certainly put those trees in a high risk category. We recommend that growers use Phytophthora resistant rootstocks like C35 or Citrumelo.
Phytophthora. Publications written in the 1970's, and again noted by our survey, showed that Phytophthora is a major culprit in the dry root rot complex. To control dry root rot, it is essential that the Phytophthora, when present, be controlled. This can be accomplished by fungicidal treatments, and by the proper application and timing of irrigation water. Overwatering creates a favorable environment for the multiplication of the Phytophthora fungus.
Gophers. It is well known that gopher damage provides entry points for Fusarium. Controlling gophers is an important factor in reducing the potential of infection by Fusarium.
We presently have no direct control for dry root rot. To control the disease, we must control the predisposing factors such as gophers, Phytophthora, poor drainage and over-watering. If the predisposing factor(s) cannot be identified for a given diseased orchard, it will indeed be difficult to control the disease. Two things are certain though: 1.) There are no chemicals to date which will control this disease; and 2.) Presently, there are no rootstocks resistant to the disease.
Listen to Akif Eskalen tell the Dry Root Rot story
The USDA has released their Fruit and Nuts Outlook Report which shows the forecast the 2019/2020 seasons and provides an overview of the markets.
The 2019/20 citrus crop is forecast to be 7.63 million tons, down 4 percent from the previous season. Declines in overall production can mostly be attributed to smaller lemon, tangerine, and mandarin crops in California. Orange production in California has remained stable since last season. Citrus production in Florida has also remained stable with a 1 percent decline in orange production, and significant increases in grapefruit, tangerine, mandarin, and tangelo production over last year. Overall decreases in production of lemons, tangerines, mandarins, and tangelos are expected to result in increased imports, and higher prices compared with last year.
Fruit and tree nut grower prices began 2020 at low levels. At 117.8 (2011=100), the January 2020 index was down 10 percent from the January 2019 index and below the January average for 2016-18 (fig.1). The January 2020 index was the lowest since January 2013. Significantly lower grower prices for citrus fruit and apples drove down the index (table 1).
As of mid-March 2020, U.S. citrus exports were down except for orange juice and tangerines. Reduced exports have increased the domestic supply of citrus, putting downward pressure on prices. The January 2020 price of all- grapefruit is down 36 percent from the year before, and all-oranges and oranges for the fresh market are down by 6.9 and 9.4 percent respectively. All- lemon prices are down 28.5 percent, and fresh lemons prices are down by 8.6 percent.
Apple prices were down 21 percent in January 2020 from the year before. USDA, National Agricultural Statistics Service (NASS) estimates the 2019 total apple crop to be up 3.6 percent from 2018. The strong dollar and increased tariffs in several countries have reduced exports, putting downward pressure on prices.
On Thursday, October 17, 2019 the University of California Cooperative Extension (UCCE) held a Lemon Rootstock and Scion workshop and field tour in Santa Paula, California. Results from Citrus Research Board (CRB) sponsored field trials evaluating several lemon rootstocks and scions were highlighted at this meeting. This event was well attended by over 100 grove managers, citrus growers and industry representatives. Speakers included CRB-funded researchers Ashraf El-kereamy, Ph.D., Mikeal Roose, Ph.D., Tracy Kahn, Ph.D., and Glenn Wright, Ph.D. The CRB has been funding research on several single site and multi-location lemon field trials, some of which have been ongoing since the late 1980's. Mikeal Roose, Tracy Kahn and Glenn Wright provided updates on the results of previous rootstock trials and the multi-location lemon rootstock and scion trials at Santa Paula, Lindcove Research and Extension Center and desert locations. Attendees learned about the various yield, packout and fruit quality of several lemon selections being studied in addition to new, non-lemon citrus cultivars to be released in the coming years. Following the presentations, attendees were invited to visit one of the lemon rootstock field trials.
Limoneira Company has been extremely helpful in much of this lemon research over the years. We thank them and also the Master Gardeners who helped in organizing the event held at the Limoneira meeting center. Read about a sideline at the event HERE.
Presentations from the workshop are available on the UCCE Ventura website HERE.