- Author: Rebecca K. Ozeran
This is the adventure of a livestock advisor trying to find a way to kill a fig tree. Normally we are doing our best to make fruit trees grow. In this case, Rebecca Ozeran had to find the best way to kill figs that were fouling the range. Her solution is not applicable to fruit tree growers in California. Triclopyr is not registered for edible fruit tree crops in CA. So, don't try this at home. There are other ways of doing it.
Mention of any pesticide in this message is not a recommendation.
Why a Livestock Advisor learned about fig trees
by Rebecca Ozeran
Livestock and Natural Resources Advisor
UCCE Fresno County
As a livestock and natural resources advisor, I don't expect to get questions about fruit trees such as figs. As it turns out, I recently needed to know just enough about figs to provide information on how to kill them - a west Fresno County landowner contacted me to ask how he could get rid of some fig trees that were threatening his belowground water pipelines.
Before writing this post, I did my due diligence and confirmed that no one has already discussed fig trees as the target of weed control on this blog. The only mentions of fig trees in the UC Weed Science blog history are a listing of approved herbicides to control weeds in California subtropical crops as of 2 years ago1 and a mention that fig was one of several crops undergoing residue trials last summer2. Triclopyr is, interestingly, not on the list of approved herbicides. (This will be important later.)
Now that we've established this, we have to ask: Why and how are we getting figs on rangelands in Fresno County? And why does it matter?
Figure 1. Mature fig trees in an orchard.
For starters, Fresno County used to have several thousand acres of cultivated figs (nearly 13,000 ac in 19663, but less than 7,500 ac as of 20164), so there are many places in the county where volunteer figs can be seen sprouting, including in newer subdivisions where fig orchards used to be, e.g. the "Fig Garden" region of the city of Fresno. Landowners also may have decided to plant figs on their rural properties as a source of fresh fruit and/or shade, and once established, the figs were able to reproduce and spread. Although fig populations seem to grow slowly in new areas, figs have invaded riparian and other natural areas throughout California's Central Valley5 and can be tough to control once established.
Of course, if fig didn't cause any problems where it grew in these natural areas, we wouldn't be talking about it today. Unfortunately, fig is capable of displacing native plants and forming thick clusters of fig where nothing else can grow5, often in riparian areas. This is problematic for livestock owners, since grazing animals don't find fully grown fig trees appetizing. This can also be bad news for the biodiversity found in riparian areas, as figs become a monoculture. In addition, fig tree clusters decrease ground cover from litter (fallen leaves, grass stems, etc.) which means the fig-dominated areas have more bare soil than grassy or shrubby areas.
Figure 2. Weedy figs create dense stands that exclude other vegetation.
Trees also tend to evapotranspire more water than herbaceous plants like grasses, so they can actually take more water from stream systems and lower stream water levels6. The combination of lower water levels and higher potential for soil erosion can then cause trouble for water quality, and especially for aquatic animals who may require certain water temperatures, clarity, or depth to survive. Lastly, there is the threat fig roots pose to water infrastructure (pipelines) as seen by the landowner who contacted me in the first place.
Hopefully at least one of those consequences helped to illustrate why someone might consider fig a weed. Fortunately for me, several Weed Workgroup members provided great information when I reached out for advice. Mechanical treatments are impractical, as fig can create new sprouts from cut stumps, stems, and roots, and repeated treatments are not always feasible. Applying glyphosate alone to the leaves is ineffective; more effective are cut stump or basal bark applications of various herbicides, including combinations listed in the informative Weed Control in Natural Areas7. Based on the book, very little is known about the efficacy of many herbicide treatments on fig itself, and treatment recommendations are based on their use in other species. Only triclopyr (told you it would be important) has been tested explicitly on fig. Triclopyr is particularly effective when applied as a basal bark treatment. A great resource explaining basal bark treatment can be found below8.
A non-UC member of the workgroup, Dr. Kerri Steenworth of USDA-ARS, referred me to Dr. Katherine Holmes, a restoration ecologist who is currently Assistant Executive Director of Solano County RCD and Chair of Solano County Weed Management Area. Dr. Holmes has investigated riparian and rangeland restoration connected to fig tree invasion in California's Central Valley5,9,10. When I spoke with Dr. Holmes, she confirmed that triclopyr basal bark treatments have been the most effective in her experience. She has never attempted stem injection or cut stump application on figs but hypothesizes that the strong sap flow would likely reduce the effectiveness of injected herbicide, and that the root system of cut and treated stumps may still be able to create new stems. Dr. Holmes suggested coating the basal 6 to 8 inches of the fig trunk with a mixture of 75% Hasten (surfactant) and 25% Garlon 4 (triclopyr), as long as the tree wasn't in or near water. Basal bark treatments require that the tree is still alive for enough time for the herbicide to be distributed through the vascular system.
In sum, fig trees are a weed issue I never imagined, but fortunately there seems to be an effective solution. More research on treating this species as a weed could be valuable, as fig production is in decline in Fresno County and fig invasion may continue in natural areas. For now, we at least have one blog post about controlling weedy fig trees.
- Weed Control in Subtropical Tree Crops. http://ucanr.edu/blogs/ucdweedscience/blogfiles/32828.pdf
- Treevix Labeled for Use in California Pomegranates. http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=21326
- 1966 Fresno County Crop Report. Available at http://www.co.fresno.ca.us/departments/agricultural-commissioner/crop-report-history.
- 2016 Fresno County Crop Report. Available at http://www.co.fresno.ca.us/departments/agricultural-commissioner/crop-report-history.
- Holmes, K. 2008. Invasive fig trees (Ficus carica) in the riparian forests of California's Central Valley: population growth, community impacts, and eradication efforts [dissertation]. Available at https://search.proquest.com/docview/304698102/previewPDF/7D691548E68B4426PQ/1?accountid=14515
- Hibbert, A. R. 1983. Water yield improvement potential by vegetation management on western rangelands. Water Resourves Bulletin 19: 375-381.
- DiTomaso, J.M., G. B. Kyser, S. R. Oneto, R. G. Wilson, S. B. Orloff, L. W. Anderson, S. D. Wright, J. A. Roncoroni, T. L. Miller, T. S. Prather, and C. Ransom. 2013. Weed Control in Natural Areas in the Western United States.
- Enloe, S., N. Loewenstein, W. Kelley, and A. Brodbeck. 2010. Basal bark herbicide treatment for invasive plants in pastures, natural areas, and forests. Alabama Cooperative Extension System, Agronomy and Soils Series. http://www.aces.edu/timelyinfo/Ag%20Soil/2010/December/Dec_2010.pdf
- Holmes, K. A. and A. M. Berry. 2009. Evaluation of off-target effects due to basal bark treatment for control of invasive fig trees (Ficus carica). Invasive Plant Science and Management 2:345-351.
- Holmes, K. A., S. E. Greco, and A. M. Berry. 2014. Pattern and process of fig (Ficus carica) invasion in a California riparian forest. Invasive Plant Science and Management 7:46-58.
- Retrieved from https://ucanr.edu/repository/fileimage.cfm?article=99170&p=HVFBYB
- Retrieved from http://figs4funforum.websitetoolbox.com/post/took-some-pictures-of-the-fig-forest-5952568.
- (C) David R. Jackson and Penn State Extension. Retrieved from https://extension.psu.edu/using-basal-bark-herbicide-applications-to-control-understory-tree-species.
- Author: Ben Faber
A fig. A yellow fig. A most delicious 'Kadota' fig. A piece of fruit that falls apart easily and shows every nick, scrape and bump.
And it doesn't take much to reduce a fig to something that is not very attractive to a consumer.
There have been all manner of packing materials that have been devised for shipping fresh figs. Nestled in individual packing hollows they can be shipped to arrive in pretty good condition.
'Bursa Black" which is a 1/4 pound fig grown in the Bursa region of Turkey is shipped to large cities in Europe and because of careful fruit selection and packaging, arrives in excellent shape at the delivery point
Some of these shipping containers pack for individual display, making it easy for the seller to keep from damaging the fruit when removed from the container.
The ultimate shipping container that has been developed for delicate fruit is a "suspended tray" container which floats the fruit to its destination. It's somewhat pricey, so the value of the fruit will determine its value to the shipper. A description of the tray using pears and avocados follows:
SUSPENDED TRAY PACKAGE FOR PROTECTING
SOFT FRUIT FROM MECHANICAL DAMAGE
J. F. Thompson, D. C. Slaughter, M. L. Arpaia
Bartlett pears and Hass avocados are subject to transport vibration damage and their susceptibility to damage
increases as the fruit soften during ripening. Firm fruit,greater than 50 SIQ units (13‐lb penetrometer firmness) for
pears and greater than 65 SIQ units (3.0‐lb penetrometer firmness) for avocados, could be shipped in a wide variety of
conventional packages with little transit vibration damage.However softer fruit sustains significant transit vibration
damage when packed in conventional packaging systems and subjected to severe in‐transit vibration conditions common to cross‐country transit in the United States. This study demonstrated that softer fruit was protected from transit vibration damage when packed in a suspended tray packaging system. The study showed that even eating‐ripefruit could be shipped in the suspended tray system with transit vibration damage not significantly greater than nonvibrated control fruit.
But hey, an egg carton may work just about as well.
- Author: Ben Faber
What a great find and it was there all along, just like a used book store can be a gold mine at times.
This is the section of Subtropical Fruit Pests by Walter Ebeling that covers avocado pests in not only California, but what was and is known to exist in other avocado growing regions around the US and the world. It was reproduced at the Hoshi Foundation's Avocadosource website. At this point it only contains the chapters pertaining to avocado. Other chapters in the full text cover citrus, grape, walnut, almond pecan, olive, fig, date and other "Minor Subtropical Fruits". The beauty of the book is not only historical, but that it is still current (although the DDT recommendations are out of date) for many pests. It also chronicles pests that have appeared in the past, disappeared and then reappeared. An example is Avocado Bud Mite - here, gone, here and seemingly gone again, probably to reappear sometime in the future. This is no replacement for the UC-IPM website, http://ipm.ucanr.edu/PMG/crops-agriculture.html , but it is a good look at how the pest has been managed in the past and is done so currently.
I thought I had the only copy of this book in Ventura County, but you could too. There are some listed on ABE Books for cheap.
This pestiferous book was compiled by Walter Ebeling at UC Riverside/Los Angeles. He was of some note, considered the Father of Urban Entomology. As you can see from the descriptions of avocado pests, he was a good all round entomologist, as well. Urban entomology really forces you to know a lot because of the diversity of arthropods in urban settings. He passed in 2010 and was recognized world-wide for his work.
Professor Emeritus of Entomology
November 26, 1907 – December 17, 2010
Walter Ebeling, world-renowned entomologist and pioneer in the field of Urban Entomology, died 17 December 2010 in a care facility in Bandon, Oregon at the age of 103. "Professor Ebeling was a legendary research entomologist," said Dr. Michael Rust, Professor of Entomology at the University of California, Riverside, who replaced Dr. Ebeling upon his retirement in 1975. "He had tremendous abilities, tireless energy, and a passion for science. He was an expert in so many fields of entomology including agriculture, physiology, and insect behavior. Dr. Ebeling helped develop Urban Entomology into a respected independent area of research."
Read more of his Memoriam: http://senate.ucr.edu/agenda/120221/IN%20MEMORIAM-Walter%20Ebeling.pdf
- Author: Brad Hanson, UC ANR Weed Specialist
Here is an updated guide for herbicides that are registered for citrus, avocado and a few other tree crops.
- Author: Jim Doyle
- Author: Louise Ferguson
The California fig industry is currently producing on about 16,000 acres. A “2002 Statistical Review” published by the California Fig Advisory Board and California Fig Institute at Fresno lists seven cultivars used primarily (although in some cases not exclusively) for dried whole figs and fig paste. These seven cultivars are Calimyrna (6,559 acres}, a four cultivar grouping identified as “Adriatics” but including Conadria, Adriatic, Di Redo and Tena (3,364 acres in combination), Kadota (1105 acres) and Mission (3702 acres). Two additional cultivars are used in California primarily for the fresh market. These are the California Brown Turkey (about 2000 acres) and a new 2005 UC release, the Sierra fig (about 200 acres). The above nine cultivars differ substantially from one another in aspects of usage, horticultural type and fruit characteristics. The Sequoia fig is being released for use in the fresh market. Although of good quality when dried, it develops both a dark skin and a dark pulp color that limits its acceptability as a dried product. Of the above nine cultivars, only five are sold fresh. These are the CA Brown Turkey, Sierra, Calimyrna, Mission and Kadota. Only these five will be compared, as follows, to the Sequoia. The four “Adriatic” class figs are used only as whole dried figs or fig paste. All are of too small a size for the fresh market.
Two horticulture types of figs are found in the California Industry. The first of these, the “Smyrna” type fig, needs to be pollinated (caprified) in order to set fruit that will persist on the tree until maturity. The Calimyrna is the only cultivar of this type grown commercially for fresh consumption in California. All of the other four fresh market figs listed above, as well as the Sequoia, are of the “common” type. These common types do not need to be pollinated in order to set and mature fruit. The advantages of the common type figs over the Smyrna type are substantial. A common type fig grower does not need to maintain caprifig trees or to buy caprifigs from other growers, does not need to treat the caprifigs to disinfect the wasps (the pollen vectors) living in the caprifigs, does not need to distribute the caprifigs throughout the Calimyrna orchard and does not have to deal with the variables or the costs of the caprification process. Climatic factors such as heat, cold, rain, wind and disease can have a substantial impact on the success of the insect vector of the pollen and the eventual level of productivity of the Calimyrna crop. A good Calimyrna orchard often produces only in the 0.5 to 1.0 ton of dried fruit range in comparison to at least twice (sometimes three times) that tonnage from common types. Were it not for the excellent quality of the Calimyrna product, when well grown, it would probably not be planted in California at all.
The CA Brown Turkey is grown almost exclusively for the fresh market. It does not dry well. The Calimyrna, Mission and Sierra are dual-purpose figs, all three dry well, with some growers often directing part of the crop to the fresh market. The Kadota is a multiple use cultivar that can be dried, canned and picked for the fresh market successfully.
Fruit Characteristics of the Five Fresh Market Figs Grown in California
The Calimyrna fig is a green-yellow to yellow skinned fig with amber pulp. As noted above, the cultivar requires caprification to set a crop. The first (Breba) crop drops without coming to maturity because caprifigs containing pollen and the vector wasp are not available at the time the Calimyrna Brebas require pollination. The second crop is abundant but of limited duration (from late August to late September in Fresno County). Fruit set coincides with the mid-summer (or profichi) flight of the fig wasp. When the flight is complete, no more fruit is set for that season. Early in maturity of the second crop, fruit size is large, although size can drop off in late September. The size of the Calimyrna fruit eye (or ostiole) is the largest of all the commercial cultivars and can range from 2.2 to 3.5 mm, allowing substantial amounts of internal insect infestation and spoilage. The cultivar is also prone to large numbers of eye splits during periods of high humidity, cool weather or rain. Fruit quality, when the fruit is grown well, sets the standard for excellence.
The California Brown Turkey is a purple-violet colored fruit with areas of yellow to yellow-green visible, especially over the fruit neck and near the fruit stem. Pulp color is a strawberry red. This cultivar is of the common type, not needing caprification. The CA Brown Turkey can set a small crop of large sized first crop (Breba) fruit. As grown in California, however, the tree is severely pruned in the winter to keep it short in height and to facilitate hand harvesting of the large second crop from the ground. This pruning essentially eliminates the first crop. The second crop is abundant and the fruit is large and retains its large size well into the harvest season. Since the CA Brown Turkey is a common type fig, once fruit production begins in late August, fruit will continue to develop and mature until fall. Production ceases only when the orchard dries out and the tree stops producing extension growth, or when a weather event (rain, frost, etc…) damages the fruit or sends the tree into dormancy. The fruit ostiole is relatively large and in some locations the fruit can be subject to insect infestation and souring. Fruit quality is good when harvested with sufficient maturity.
The Mission fig is a violet-black colored fig with the coloration usually covering the entire fruit surface. Pulp color is a strawberry red. This cultivar is a common type fig not needing caprification. The cultivar usually sets a good crop of Breba fruit that are large in size and of very good quality. These Mission Brebas are often harvested from orchards that have been established to produce fruit for drying. Such trees are often very large and picking can be difficult and expensive. The Mission second crop is abundant and also of very good quality. Fruit size of the second crop is large enough to pack fresh for a week or two, but then size diminishes rapidly, eliminating its use for the fresh market. The fruit ostiole of both the Breba and second crop is quite small and fruit spoilage is usually not a problem. Fruit quality of both crops is very good.
The Kadota fig is a medium sized greenish-yellow skinned fruit that is grown only in limited quantity for the California fresh market. Pulp color is amber. The Kadota is a common type fig. Production of a Breba crop can be variable, from light to good in volume. The second crop is abundant but most fruit is too small to be valuable for picking fresh. Towards the end of the season many small, dry, commercially worthless fruit, known as “puffballs”, can be present. The fruit ostiole is medium in size, partially restricting insect access. Fruit quality of the Brebas and second crop is sweet and good.
The Sierra fig is a new cultivar, released for planting to California growers by UC in 2005. Although developed as a high quality fig for drying, initial plantings are being made for the fresh market so that the new cultivar appears to be suitable for both purposes. Skin color of the Sierra is a yellow-green and pulp color is amber. The Sierra is a common type fig. The Breba crop of Sierra to date does not appear to have commercial value. The Breba crop has been light and the figs produced have not been particularly large or highly flavored. The second crop, however, is abundant. The fruit is medium to large in size and holds fruit size well into the fall. The fruit ostiole is very tight, effectively restricting insect access to the fruit interior. Fruit flavor is very good.
The new Sequoia cultivar that is proposed for plant protection and release to the California fig industry has been developed for the fresh market. The fruit is yellow-green in skin color with reddish-amber pulp. This skin color is competitive with the yellow-green Calimyrna, Kadota and Sierra but complimentary to the violet-black colored CA Brown Turkey and Mission. The Sequoia is a common type fig. This gives it an advantage over the Smyrna type Calimyrna in productivity and production efficiency. The Breba crop of Sequoia ranges from light to medium in volume. The Brebas are large in size with very good quality. The production of saleable Brebas gives the Sequoia an advantage over the Calimyrna, CA Brown Turkey and Sierra cultivars that either develop very few or no Brebas at all. The second crop of Sequoia is abundant with large to medium size. The Sequoia appears to maintain fruit size well into the fall in contrast to the small late-season fruit size of the Mission and Kadota and the absence of fruit on the Calimyrna. The ostiole or eye of the Sequoia is very tight, similar to the Sierra and Mission but substantially tighter than the Calimyrna, CA Brown Turkey and Kadota. The fruit flavor and quality of the Sequoia is as good as or better than all of the five established cultivars listed here with the exception of the Calimyrna. The Sequoia, which has Calimyrna in its pedigree, approaches the flavor of Calimyrna, but the Calimyrna, with all of its many production problems, still retains its position as the premier quality fig.