The UC Kearney Agricultural Research and Extension Center has a presence at what is billed the world's largest agricultural exposition, the World Ag Expo in Tulare, Calif., Feb. 14-16, 2012.

The production costs for peaches grown in California are heavily dependent on the costs of hand labor for pruning, thinning and harvest. This work takes a lot of time in part because farmworkers must climb up and down ladders and reposition the ladders as they move through the orchard.

UC Kearney Agricultural Research and Extension Center scientists have found that production costs can be cut dramatically by growing “dwarf” trees that minimize the need for ladder access. However, the limiting factor for peaches has been the lack of acceptable dwarfing rootstocks for the best peach varieties.

In 1987, UC and USDA scientists began a landmark rootstock evaluation project. More than 100 varieties that were either collected or bred by USDA plant breeder David Ramming were planted at Kearney. Five trees each of O'Henry peach and Santa Rosa plum were grafted on the rootstocks and extensively evaluated over the next seven years.

For peach, eight selections showed good potential as dwarfing or semi-dwarfing rootstocks and were propagated for further evaluation. In 2004, two of these were patented as the slightly dwarfing rootstock, “Controller 9,” and the very dwarfing rootstock, “Controller 5.”

At UC Davis, now retired researcher Fred Bliss bred rootstocks using Harrow Blood and Okinawa as parents. UC Davis pomologist Ted De Jong has taken over the program, which patented and released three new rootstocks: Controller 7, Controller 8 and Controller 9.5. A fourth, Controller 6, will be released soon.

The research blocks with Controller 6, 7, 8, and 9.5 at Kearney are continuing to be monitored for production performance and sustained productivity. So far, their performance looks positive but, because of funding cuts, the long-term outlook for maintaining the plots is questionable, De Jong said. UC Cooperative Extension farm advisor Kevin Day is conducting trials of “controller” rootstocks in conjunction with growers to help them determine which ones best fit their farming operations.

De Jong said there is significant interest in Controller 9 because it has been available the longest. Trees on Controller 9 are only slightly reduced in size but require significantly less pruning than trees on the standard rootstock, Nemaguard. There is also substantial interest in Controller 6 by growers who are more aggressive in their interest in smaller trees. Controller 6 causes a substantial reduction in tree size without reducing fruit size.

“I think that Controller 7 may be an optimal choice for many growers because it offers modest size-control and trees on it have had excellent production characteristics and is not such a large leap to a smaller tree,” De Jong said. “However there has been limited interest in it thus far.”

Controller 5 likely makes trees too small for commercial California peach production and trees on it tend to produce smaller fruit. However, it has good potential for home gardeners who have limited space, prefer not to prune much and aren’t very concerned about fruit size.

De Jong, Day, UC Davis pomology specialist Scott Johnson and numerous students have conducted extensive research concerning the dwarfing mechanism involved in these rootstocks and published more than 10 scientific articles on different aspects of the research. These articles and more information about the California Rootstock Breeding Program are available on the UC Fruit Report website.

Applying composted green waste to a field before solarization is more effective for killing weed seeds than solarization alone, according to the preliminary findings of research conducted at the UC Kearney Agricultural Research and Extension Center last summer.

Soil solarization involves covering a field with clear plastic mulch to trap solar radiation in moist soil. During the hot summer months, the soil temperature can rise to levels that can kill soilborne diseases, nematodes and weed seeds. This system has proven especially useful to small-scale, limited-resource and organic growers who produce specialty crops in warm climates.

Last summer’s research, coordinated by Kearney-based integrated pest management plant pathologist Jim Stapleton, was part of a bi-national, multi-institution collaborative effort led by UC Davis biological and agricultural engineering professor Jean VanderGheynst. The research was funded with a grant from the Binational Agricultural Research and Development Fund, which supports agricultural research in Israel and the U.S. that is mutually beneficial.

Environmental science students at Fresno Pacific University, under the supervision of professor and project collaborator Ruth Dahlquist, were enlisted to carry out some of the research on micro plots at Kearney. They subjected black mustard seed to a solarization regimen that mimicked typical farming conditions to study the effects of the treatment on the seeds and the physical and biological properties of the soil.

“Municipal green waste is a huge byproduct of civilization,” Stapleton said. “We would like to increase the agricultural use of this compost by devising ways to maximize its pesticidal and other beneficial properties.”

Two of the Fresno Pacific students were honored by the California Weed Science Society at its annual meeting in January for posters they developed based on their research findings. DeeAnn Kroeker earned first place in the student poster contest for her analysis of the effects of volatiles produced during solarization of compost-amended soil on black mustard seed inactivation. Kate Hernandez was awarded third place for her poster about the field effects of solarization and compost treatment on inactivation of black mustard seed.

The research at Kearney continues during the summer of 2012.

The Israeli counterpart of the solarization research is focused on the impact of a different type of compost and solarization on fungal plant pathogens in the soil.

The Geographic Information Systems (GIS) team at the Kearney Agricultural Research and Extension Center is growing this year. The program will add two positions in the coming months with new grant funding as more scientists recognize the value of employing spatial mapping in their agricultural research, said Kris Lynn-Patterson, the GIS Academic Coordinator at Kearney.

GIS is giving researchers and growers a whole new perspective of the land. GIS software enables users to attach landscape attributes to digital maps, which are then overlaid onto aerial photos and satellite images. With GIS and image processing, the viewer can see trends and patterns that aren’t visible from the ground.

In one of the new projects, the Kearney GIS team will work with Beth Grafton-Cardwell, a UC Riverside citrus entomology specialist and director of the UC Lindcove Research and Extension Center, to provide the spatial information necessary to better manage Asian citrus psyllid (ACP) and the possible future occurrence of Huanglongbing, a devastating citrus disease that the psyllid can spread. ACP was introduced into California in 2008; large populations are now established in urban areas of San Diego, Imperial, Los Angeles, San Bernardino and Riverside counties. Huanglongbing has not been detected in California to date. The California Department of Food and Agriculture and citrus growers are treating urban and agricultural areas of infestation to prevent ACP spread and Huanglongbing introduction.

GIS will be used to document the locations of ACP infestations and the disease, and analyze the risk and rate of spread from the urban areas into commercial citrus. The research is funded by a five-year grant from UC Agriculture and Natural Resources to conduct risk assessment, economic analysis  and extension education for Asian citrus psyllid and Huanglongbing disease management in California.

Kearney GIS also secured a contract with the Citrus Research Board to map all commercial citrus orchard locations and boundaries in California.

“This will go hand in hand with the Asian citrus psyllid research,” Lynn-Patterson said. “Currently a seamless GIS map layer of this type doesn’t exist, but is badly needed to facilitate the effective use of GIS in an area-wide pest management program.”

Another source of funding for the GIS program has been Cotton Incorporated and the California Cotton Alliance for continuing work with Kearney-based UC integrated pest management advisor Pete Goodell. GIS is critical to understanding the movement of lygus bugs through the San Joaquin Valley’s diverse cropping landscapes and the relationship between crops that act as sources (places from which lygus originate) or sinks (crops into which lygus move).  Throughout the year, lygus feed on various crops and weeds, and when these become unsuitable, they move into cotton, where lygus costs farmers nearly $19 million in yield loss each year.

The GIS team will build on the existing Lygus Community Mapping Program by incorporating lygus monitoring data, and delivering the program through smart mobile devices, such as 3G- and 4G-compatible cell phones and tablets.

See Kearney’s Web-based GIS website for more information on the program.