- Author: Jeffrey P Mitchell
- Author: Anil Shrestha, California State University, Fresno
- Author: Jeffery A. Dahlberg
- Author: Lynn Epstein
Since the advent of irrigation in California with the widespread drilling of wells in the 1930s and the proliferation of orchard crops during the past two decades, total annual water use in many watersheds exceeds supply. Partly as a consequence, California enacted the Sustainable Groundwater Management Act in 2014, which limits withdrawals to replenished levels.
Because irrigated agriculture accounts for nearly 80% of total water use, reductions in irrigation will be required, but preferably without decreasing either productivity or food supply. Furthermore, with some climate change projections suggesting a potential 20% water loss by the middle of the century, the need for more efficient water use could become acute. Fortunately, some water-saving methods such as drip irrigation have been supported by the government and there have been programs that have increased implementation and farmers understand these methods well.
Reduced disturbance tillage, or no-till, however, also offers an under-utilized strategy for increasing agricultural water use efficiency in California. There has been very little research and there is very little information available to farmers on no-till production systems for the diverse array of crops that have been produced in the state historically.
UC Cooperative Extension cropping systems specialist Jeff Mitchell led a diverse team of ANR, farmer, private sector and other public agency partners to evaluate the potential for producing sorghum and garbanzos, using high residue, no-till techniques in the San Joaquin Valley in a four-year study conducted at ANR's ag experiment station in Five Points, Calif.
Standard tillage practices have been used throughout the region for nearly 90 years. Using similar inputs and amounts and pest management, they showed that a garbanzo and sorghum rotation in no-till yielded at least as well as in standard tillage.
Sorghum yields were similar in no-till and standard tillage systems while garbanzo yields matched or exceeded no-till than in standard tillage, depending on the year.
In the trial, no-till garbanzos yielded an average of 3,417 pounds per acre versus standard tillage with an average of 2,738 pounds per acre; garbanzo production in California, which is almost all in standard till, averages 2,300 pounds per acre.
We envision that if water costs continue to rise and as curtailments on water supply increase, the value of agricultural land in California will eventually decline, providing more of an economic incentive for using no-till for growing a portfolio of crops, such as sorghum and garbanzo, amenable to these pending constraints on irrigation.
In addition, there already exists high acreage of relatively low-value field crops in the state. As annual row crop farmers are faced with the need to reduce water use, knowing which field crops perform well in no-tillage conditions is important for the region. For this reason, this work may serve as a decision-making tool for growers in the future, especially if there is the opportunity to both reduce management costs and maintain yields
An outgrowth of this work on no-till systems is the group of about 15 farmers who're now a part of a USDA NRCS Conservation Innovation Grant Program project that is looking at opportunities and approaches for reducing disturbance in organic vegetable production systems.
- Author: Kathy Keatley Garvey
Especially those oleander aphids that suck the very lifeblood out of our milkweed plants that we're struggling to save for monarch butterflies.
Just call aphids "The Enemy of the Gardener" or "The Enemy of the Milkweed."
The University of California Statewide Integrated Pest Management Program (UC IPM) describes aphids as "small, soft-bodied insects with long slender mouthparts that they use to pierce stems, leaves, and other tender plant parts and suck out fluids. Almost every plant has one or more aphid species that occasionally feed on it."
"Aphids have soft pear-shaped bodies with long legs and antennae and may be green, yellow, brown, red, or black depending on the species and the plants they feed on," UC IPM tells us. "A few species appear waxy or woolly due to the secretion of a waxy white or gray substance over their body surface. Most species have a pair of tubelike structures called cornicles projecting backward out of the hind end of their body. The presence of cornicles distinguishes aphids from all other insects.
"Generally adult aphids are wingless, but most species also occur in winged forms, especially when populations are high or during spring and fall. The ability to produce winged individuals provides the pest with a way to disperse to other plants when the quality of the food source deteriorates."
Not only do aphids stunt plant growth but they can spread viruses. Plus, they produce that sticky honey dew they that attracts ants and other insects.
Density? We've seen aphids so dense on our milkweed stems that all we see is yellow. (Sometimes we see red!)
We recently saw them magnified on a Leica DVM6 microscope, operated by Lynn Epstein, UC Davis emeritus professor of plant pathology, at a demonstration in Hutchison Hall. (See image below)
In California, most aphids reproduce asexually throughout most of the year, according to UC IPM. Did you know that a single aphid can generate as many as 12 offspring a day--without mating?
Bring on the lady beetles (aka lady bugs), lacewings, and soldier beetles! The larvae of lady beetles and syrphid flies also do their part in gobbling up aphids.
What to do when biological control doesn't work that well? Or when your lady beetles depart? Pinch the aphids; spray them with with water; or spray them with a mixture of 1 tablespoon of dish soap (Castile liquid soap) and one quart of water. Some folks dab aphids with cotton swabs dipped in isopropyl (rubbing) alcohol but that will kill the monarch eggs and larvae as well. We've found that spraying a mixture of sudsy soap and water works best for us.
Lather is the best medicine.