Protecting Melons From Silver Leaf Whitefly

Avoid Planting Near Earlier Planted Crops

By Patrick Cavanaugh, Editor

Silver leaf whitefly can be a severe yield-robbing pest in melons, but there are ways to prevent the damage, according to Tom Turini, a UCANR Vegetable Crops Adviser in Fresno County.

“A tactic is going to depend upon planting. If you’re able to put the crop into an area where you’re not next to earlier planted melons or cotton or known sources of whitefly, your likelihood of experiencing damaging whitefly levels is going to be lower,” Turini said. “Growers can’t always do that, but that’s part of the approach when you can. You’ll limit your risk.”

Tom Turini, UCANR Farm Advisor, Fresno County

Turini said the pest could mainly be a problem when you’re putting in those late melon fields when whitefly populations are higher.

“Whiteflies are not good fliers, so when you put those fields in areas where you don’t have sources of whitefly nearby then you will have less pressure for sure,” Turini said.

“Then there are some insecticide programs that you can look at, particularly when you know you’re going to have pressure,” Turini explained. “If you’re coming into high temperatures, and you’ve got late-planted melons, you may want to start with soil-applied insecticides, through the drip. It could be Admire; also Sivanto is a newer material that that has registration and has shown efficacy in desert production areas, which have much higher pressures and more consistent pressures than we do in the San Joaquin Valley.”

Healthy Soils Initiative Looks at Cover Crops

Cover Crops Between Annual Veg Crops Studied

 By Patrick Cavanaugh, Editor

Research is under way to determine if using cover crops between two annual vegetable crops will improve the soil for future crops. It’s all part of the California Department of Food and Ag Healthy Soils Program—a statewide project.

Amber Vinchesi is a UCANR Vegetable Crops Farm Advisor in Colusa, Sutter and Yuba counties. She works mainly with processing tomatoes but also with growers farming vegetables for seed as well as fresh market vegetables such as honeydew and cantaloupe melons.

Vinchesi is collaborating with California’s Healthy Soils Initiative, a partnership of state agencies and departments led by the CDFA Healthy Soils Project. It’s a combination of innovative farm and land management practices that may contribute to building adequate soil organic matter that may increase carbon sequestration and reduce overall greenhouse gases.

“We have three sites, and the site that I’m working on is focused on winter cover crops between crops such as wheat, tomato or corn, to improve soil health,” said Vinchesi, who is being assisted by her colleague Sarah Light, the agronomy advisor in Sutter, Yuba, and Colusa counties

Other Healthy Soil sites are located in the Delta area, and overseen by Michelle Leinfelder-Miles, UCANR Delta Crops Resource Management Advisor in San Joaquin County. Brenna Aegerter, a UCANR Vegetable Crops Farm Advisor also in San Joaquin County, is working with Leinfelder-Miles. Additionally, Scott Stoddard a UCANR Vegetable Crops Farm Advisor in Merced County has a site.

The cover crop will be vetch, a legume.

“We hope that it will put nitrogen and biomass into the soil,” Vinchesi said. “We’re not sure what the results will be, but we hope it will help with aggregate stability, water infiltration, and even reduce weed density.”

She noted that the trial, which is in the first year of a three-year project, will include two different seeding rates, a high and low rate, and then an untreated control where there’s no cover crop.

“And we’ll do soil testing to see how things change in the soil over time,” she explained.

Replanting Trees as Harvest Ends

David Doll on Replanting Trees

By Laurie Greene, Editor

As harvest comes to a close for many tree crops, the time for replanting trees is swiftly approaching. David Doll, a UC Cooperative Extension farm advisor in Merced County, said that if California receives significant rain this year, the replanting process in orchards would be more difficult.

“If we are potentially coming into a wet winter, it’s going to provide challenges in establishing new orchards,” Doll said. “In the case of heavy rainfall, it’s important to keep a few things in mind and plan accordingly. First, if we’re doing any type of soil modification, we need to get a little bit of moisture to help the soil settle.”

Doll said second step is ‘pulling’ berms—the small hills or walls of dirt or sand in an orchard created to divert rain and irrigation water from the tree trunk. He explained, “We want to pull them before the soil gets too wet. We don’t want to walk into a heavy soil field, such as clay or clay loam, and pull berms because in doing so do, we would actually slick that soil over and have to deal with compaction and future issues with the orchard.”

“Third, when we start planting our trees,” Doll said, “it’s important to make sure that we dig a proper hole with wet soils.” Doll warned if you don’t spend the time to dig a hole,  you can ‘glaze’ the soil or form a crust on the sides of the holes, particularly in clay soils, leaving a hard, compact surface that is impenetrable to young roots. He advised to fracture or scratch glazed soil on the sides of the hole with a shovel or rake before filling in to ensure proper root growth.

Doll also said that when planting, the graft union—the point on a plant where the graft is joined to the rootstock—needs to be kept aboveground. “Countless times I’ve seen people plant the graft union below the ground,” said Doll. “Or they’ll plant the tree, pull up a berm, and actually put the graft union below the ground. Keeping the graft union about one hand’s width above the soil line will ensure the graft union remains aboveground as the tree settles.”

“Lastly, if machine planting in very wet clay loam soil, clods [lumps] and air pockets may form,” Doll said. “That’s problematic. The same thing also may occur with hand planting. It’s important to make sure the planters are digging a properly-sized hole and the roots need to be sufficiently covered. The soil needs to be broken down and then replaced around the tree. Finally, to ‘tank’ the tree, apply about 4-5 gallons of water after replacing the dirt to reduce the air pockets and allow the tree to get a good, solid start.”

Fresno State Plant Science Students Earn top Honors at UC Davis Weed Day

A team of four Fresno State plant science students took first place in the weed identification category at the 58th annual Weed Day seminar hosted by University of California, Davis.

Seniors Sarah Parry of Sonora, Isaac Giron of Terra Bella and Mala Tu of Cambodia and graduate student Rama Paudel of Nepal correctly identified 17 of 20 weeds to win the contest among almost 200 students on July 10.

Students were asked to identify different types of weeds during a tour of current weed research plots at UC Davis. The plots involved herbicide research in annual fruit and vegetables crops, crop safety and herbicide symptomology demonstrations, aquatic weeds and grassland weed invasion and restoration research.

The students were invited to a dinner after the seminar for one-on-one interaction with UC Davis weed science graduate and post-doctoral students, extension specialists and professors.

“It was a great experience that opened my eyes to new opportunities in weed science and it has encouraged me to pursue my master’s degree,” Perry said. “I’m excited to see what the future has in store.”

Each year, Weed Day brings together pest control advisors, farm advisors, chemical company cooperators, college faculty and students and regulatory officials to learn about current weed science research at UC Davis.

For more information, contact Steve Wright, farm advisor at sdwright@ucdavis.edu or 559.684.3315.