With the drought our perpetual salt problems are exacerbated due to less water and often more saline water. The question keeps coming up if gypsum (calcium sulfate) can help correct the problem. And the answer is maybe, but along the coast, probably not. The problem there is confusion about what is a saline soil and what is a sodic soil. A saline soil is one that is dominated by salts, but has a pH below 8.5 and can have a white crust that will actually taste salty. A sodic soil is one dominated by sodium, has a pH above 8.5 and can be saline, as well. Often though, there is a brownish cast to the surface salt crust. This is caused by dispersion (dissolved) of soil organic matter caused by the high pH. It's like cooking with vinegar when you make ceviche out of fish. Saline soils often have a high calcium content and may have sodium, but at a very low ratio compared to calcium. Most of the sodic soils in California are found in the Central and Imperial Valleys. Along the coast, the soils, if they have a problem, are largely saline.
The way gypsum works, is that the added calcium displaces soil sodium, pushing it lower in the soil column. The process also requires a lot of water to move the sodium through the soil column.
So the answer is, along the coast, gypsum is unlikely to improve soil conditions. However, there are other instances where it might help. In the San Luis Obispo area there are lots of serpentine derived soils that have a high magnesium content relative to calcium. And they commonly aren't saline, just an imbalance between the two cations. This can lead to infiltration problems and calcium deficiency in plants. Apples are especially sensitive to this high Mg:Ca ratio and develop a condition called “bitter pit”, a surface, brown pitting in the skin. There are other crops, like celery that are especially sensitive, but even avocado can be mildly affected. In the case of magnesium imbalance, gypsum can help.
The UC IPM Green Bulletin is a very useful guide to many things pest, weed and disease management. The latest edition is now out.
Check it out. www.ipm.ucdavis.edu/greenbulletin
Pest Note Updates | Page 2
Understanding Neem- | Page 3
The Good Side of | Page 4
Ask the Expert! | Page 6
SIGN UP…for a free subscription to the Green Bulletin at http://ucanr.edu/subscribegreenbulletin
- Author: Gary S. Bender
I just raked up all the leaves under the avocado and it looks so nice. PUT THEM RIGHT BACK. The avocado is shallow-rooted and really depends on the natural leaf mulch to protect its roots. In fact the roots will actually colonize the rotted leaves as if it were soil. This mulch is also a first line of defense against root rot. The decomposing leaves create a hostile environment to the microorganism that causes the disease. The mulch also helps to reduce evaporative loss of water and therefore reduces water needs. Avocado growers will actually spread mulch in cases where trees are too young to produce adequate leaf drop for mulch or in windy areas where mulch has blown away. The key to remember is that the mulch should be kept at least six inches away from the trunk to avoid collar rot which can be causes by keeping a moist mulch against the trunk.
- Author: Gary Bender
Farmers in our county who are using high-priced water are really thinking about “niches” in the market. They
simply must get the best prices they can if they are going to stay in business.
So, what are these “niches”? One niche is simply converting to an organic operation. This can usually mean higher prices, but the increase in cultural costs must be carefully considered (spraying glyphosate for weed control is a lot cheaper than hoeing, but glyphosate is not organic!). It can be an early variety that hits the market ahead of other areas (early season, low-chill blueberries), or it can be a crop that is later than other farming districts (Gold Nugget mandarins), or it can be a crop that is desired by a local market (tropical guavas for the Hispanic population).
We might have a niche local market for hops developing right before our eyes. According to Wikepedia, San Diego has 87 craft breweries and brewpubs, with 31 more on the drawing boards. I have heard that our local craft beer makers might like to buy local hops.
But, can they be grown here? Over the last 30 years I have tried to steer growers away from growing crops that have a high chilling requirement. I've talked would-be pistachio and cherry growers from planting because they both have winter chilling requirements in excess of 900-1000 hrs below 45 F. In the case of hops, they have a chilling requirement and we think a long daylight requirement, which they get in the Northern climates. And I've told a lot of people that hops don't do well south of San Francisco (because that's what I read on the internet). But some people planted hops anyway, and guess what! They do grow here!
But they don't always bear fruit (cones). Local growers have told me that ‘Willamette', ‘Centennial' and ‘Northern Brewer' do not produce well. But ‘Cascade' and ‘Nugget' have been producing from young vines at the Star B Ranch in Ramona. And other growers have been able to produce with 'Chinook', ‘Galena', ‘Perle' and ‘Tomahawk'. Now, will they produce the quantities needed to compete in a commercial market, pay the water bills and make a profit? This sounds like a farm advisor trial in the making!
You may wish to read a good article on growing hops that was prepared by Gordon W. Morehead and Paul Vossen with UCCE in Sonoma County http://cesonoma.ucanr.edu/files/27166.pdf.
Growing Hops. Hops are usually started from rhizomes (root cuttings) planted in hills about five feet apart in the early spring. Hops grow quickly as vines on a tall trellis. Most growers erect poles about 16-20' tall, run wires between them and drop stings down about five feet apart for the vines to climb. Three trainings are done every fifteen days to get the vines to grow up the stings properly.
For irrigation a local grower in San Diego has reported to me that (in her second year) she used drip irrigation with a 1 gal/hr dripper/plant for 20 hrs in a set, two sets per week. She fertilized 3 times per season with 1 lb 5-1-1 organic fertilizer and liquid fish emulsion (not sure how much) through the irrigation system. She just completed her second year so I'm not sure what her water and fertilizer requirements will be in the third year when the vines are in full production.
Harvesting is done in August-September by cutting down the vines and either taking them to a machine that separated the cones from the leaves and vines, or by hand. In her case she bought a harvester for $14,000 that “is a necessity if you have a lot of vines”. Depending on the requirement of the buyer, the grower may have to dry the cones and chop them. The grower should work out the marketing requirements well in advance of the harvest.
Are hops going to make it as a new crop in San Diego? We don't know, but stay tuned!