The rains are gone and the hills are drying. The weeds in the orchards that aren't being hit by the irrigation water are drying up, as well. During winter and early spring, false chinch bug primarily feeds on foliage, stems, and seeds of wild grasses and cruciferous weeds. When vegetation dries or is cut, or weeds are treated with a herbicide, bugs move in large numbers to feed on virtually any nearby green plants, including irrigated avocados and citrus. These feeding aggregations can be very large. And the calls come in. Why they are called "false" is hard to say, because they can sure seem real.
The false chinch bug (family Lygaeidae) adult (above) is mostly light to dark gray, elongate, and about 0.12 inch (3 mm) long. Females lay eggs on host plants or in cracks in soil. The mostly pale gray nymphs
have inconspicuous reddish to brown abdominal markings. There are from four to seven generations per year. All stages can be present throughout the year.
False chinch bug occasionally causes severe injury on young trees by sucking sap from shoots and young stems. Infested shoots wither and die suddenly after attack, which typically occurs in May and June. Economic damage normally occurs in groves away from the coast only on young trees in border rows adjacent to uncultivated areas or grasslands. Otherwise healthy mature trees tolerate bug feeding.
So what to do? Monitor during late winter and early spring if young avocado/citrus trees are growing inland near unmanaged areas most susceptible to false chinch bug migrations. Before winter weeds dry or are cut, look for bugs on fences and weedy areas adjacent to young trees.
If false chinch bugs are common, consider treating weedy borders to kill bugs before they migrate. Only border trees may need treatment.
There are other insects that can cause these feeding symptoms, such as stinkbugs, and leaf blight can look very similar to the feeding damage that these insects do. So make sure, it is false chinch bug that is causing the problem and not an irrigation issue.
Nitrogen is the nutrient plants require in the largest quantity for better yield and quality. Nitrogen is also an integral constituent of proteins, nucleic acids, chlorophyll, co-enzymes, phytohormones,and secondary metabolites, and its deficiency can negatively affect yield. Nitrogen-deficient plants are stunted, with narrow, small, pale leaves. Excessive N application increases vegetative growth and susceptibility to diseases that infect fruit, kill spurs, and reduce yields in subsequent years. Managing nitrogen is critical to tree health and productivity, and active understanding of how it plays in the general horticulture of the tree is critical.
In response to evidence of nitrate pollution of groundwater in California, the various Regional Water Quality Control Boards have adopted regulatory programs to protect groundwater resources that requires growers to use best nitrogen (N) management practices to reduce nitrate loading. As a help to growers, this publication has been created to optimize N use efficiency in citrus and avocado crops with the outcome of reducing N leaching.
UC Riverside has entered into a $2.25 million partnership with Spain-based Eurosemillas S.A., a global leader in the commercialization of agriculture innovations, to help the university bring to market the most promising and advanced avocado scions and rootstocks in its collection.
If successful, these varieties would meet diverse regional growing requirements, exhibit better post-harvest characteristics, increase yields, provide resistance against disease, and expand consumer market diversity.
“Eurosemillas has successfully commercialized citrus varieties developed at UC Riverside in the past. They have the global network and expertise to do the same with the next generation of avocados,” said Brian Suh, director of technology commercialization in the Office of Technology Partnerships at UC Riverside, who worked with a team on this initiative for the past four years.
Eurosemillas will obtain access to a small subset of the overall university avocado variety and rootstock collection for evaluation and testing on various continents to see if they perform as well as they do in California. At the same time, they will forge partnerships for commercialization that could lead to global market penetration of some of these selections.
“After 31 years of working with UC on many other crops, we are delighted to partner with UCR again in a new product like avocado,” said Javier Cano Pecci, Chief Executive and Development Officer of Eurosemillas. “The avocado market is growing and is currently dominated by the Hass variety. This is a great opportunity for growers, marketers, retailers, and consumers to have options and diversify to include better avocado varieties and rootstocks adapted to their regions.”
UC Riverside's 70-year old avocado breeding programs house one of the most elite germplasm collections of scion and rootstock breeding material in the world. The University of California has partnered with California avocado growers since the inception of the industry a century ago and has had several plant breeders developing new varieties and rootstocks for the industry.
Bob Bergh headed the variety improvement program for nearly 40 years, which released among other varieties, the ‘Lamb Hass' and ‘GEM.' This program is under the leadership of Mary Lu Arpaia, an extension horticulturist. The goal of the variety breeding program is to develop trees with high eating and market quality while increasing yield efficiency.
Arpaia said for the California industry to remain viable, growers must have new varieties that yield more than Hass, are more tolerant to environmental stress, and can be produced reliably under high-density planting systems.
“I am delighted by this partnership with Eurosemillas since it will help UC take this vision for the future toward reality,” Arpaia said.
The variety improvement program has four selections being readied for release that can augment the ‘Hass' variety in terms of seasonality and have potential for expanded environmental adaptation within California.
The rootstock breeding program was started in the 1940s by George Zentmyer and is currently directed by Patricia Manosalva, an assistant professor of plant pathology at UCR. The UCR Rootstock Breeding Program is one of the few well-recognized rootstock breeding programs worldwide and has been historically funded by the California industry through the California Avocado Commission. The main goal of the rootstock program is to develop and release the next generation of rootstocks that meet the most pressing needs of growers using traditional breeding complemented with genomic-assisted breeding approaches.
The program is selecting rootstocks that can resist Phytophthora root rot, the most common avocado disease worldwide, as well as salinity, drought, and heat, all of which are expected to become worse as the climate warms. In collaboration with the California Avocado Commission, five UC Riverside advanced rootstocks exhibiting resistance to these major challenges are being evaluated by growers throughout California.
“This partnership with Eurosemillas will allow us to test our five advanced rootstocks in combination with ‘Hass' and local scions in other countries to determine their potential outside California,” Manosalva said.
Peggy Mauk, director of agricultural operations and cooperative extension horticulture specialist, has been active in avocado research and extension for more than two decades. Over the past 25 years, avocado production in California and worldwide has been challenged by declining water quality. Avocado is the most salinity sensitive tree crop and ‘Hass' is very susceptible to damage caused by salts. She initiated a program to find rootstocks tolerant to saline water.
“Our UCR team in partnership with Eurosemillas is focused on finding rootstock/scion combinations that increase salinity tolerance,” Mauk said.
Over the last 30 years, the avocado market has increased 2.5-fold and per capita consumption has quadrupled, generating interest in avocado production in many other countries, Manosalva said. But diseases, climate change, and the worldwide market's dependence on the Hass variety threaten this burgeoning market.
“The funding from Eurosemillas will allow UC Riverside to maintain the plant material and support and complement the current California Avocado Commission funding of the avocado scion and rootstock breeding programs, respectively, which have significant value given their uniqueness,” said Kathryn Uhrich, dean of UC Riverside's College of Natural and Agricultural Sciences.
Avocado Varieties like GEM, Maluma, and Future Varieties
& Rootstock Update
CAS/CAC/UC Seminar Series
Mary Lu Arpaia and Eric Focht of UC Riverside Botany will cover the horticultural characteristics of the Hass-like varieties - how they grow in different circumstances relative to ‘Hass'. Patricia Manosalva of UCR Plant Pathology will cover the avocado rootstock breeding program and the efficacy of root rot chemicals, new and old.
June 10, 9-11 AM, Wednesday. A virtual seminar, viewed on your own computer at home or work.