We hear often of exotics pests and invasive species. We know that plants, pests and disease can spread in many ways. We also know new problems arrive regularly – seemingly with increasing speed.

In the Ventura County UCCE office people often show up with samples of soil, plants, and insects. We would like to take this opportunity to remind people that moving these, and related items, across geographical borders (countries, states and counties) often require permits. Permits may even be required when working with government agencies. Not obtaining a permit when required can lead to unpleasant consequences including: regulatory action, fines, or loss of research funding.

To help protect yourself and reduce the spread of exotic and invasive species, please do not move samples across geographical borders without checking if a permit is required. UC ANR Safety Note #146, “Quarantined and Regulated Pest Permit Requirements” can help. It can be found at http://groups.ucanr.org/ehs/files/68310.pdf.

Other UC ANR safety topics can be found at http://groups.ucanr.org/ehs/Safety_Notes/.

Ventura County UCCE Staff Research Associate Maren Mochizuki shares with us how monitoring spore traps in avocado orchards can lead to better understanding and management of disease.

An important component of integrated pest management is frequent monitoring to understand which, if any, pests are present and at what time of year.  In collaboration with Akif Eskalen a researcher at UC Riverside, Ben Faber, Ventura County UCCE Farm Advisor and Maren Mochizuki, Ventura County UCCE Staff Research Associate are sampling in three avocado orchards in Ventura and Santa Barbara counties using traps that catch spores, reproductive structures for many disease-causing organisms in avocado such as Dothiorella and Phytophthora

The spore traps consist of glass microscope slides suspended at two heights in the avocado tree canopy.  Every two weeks, we remove the slide and replace it with a fresh one; researchers at UC Riverside examine and identify the spores under a microscope.  We hope to improve our understanding of the life cycles of these spore-producing organisms for more effective disease management.

Young avocado tree killed by Dothiorella canker,

White, powdery exudates from a Dothiorella canker

Healthy green avocado foliage (right) next to the pale, yellow foliage of a tree with Phytophthora root rot

To protect water resources and comply with increasing regulation, greenhouse managers are wise to make changes to prevent pollutants, such as fertilizers, pesticides, and container media from ending up in surface and ground waters. One way to do this is to use vegetated buffers.

Vegetated buffers are areas or strips of land maintained in permanent vegetation to prevent erosion and improve water quality by trapping and treating contaminants. Vegetative buffers can also provide many other benefits such as increasing beneficial insects for biological control of crop pests and protecting streambanks. In addition, they can be used for green waste and secondary crop production.

Some examples include vegetated buffers are bioswales, vegetated filter strips, and constructed wetlands.

• A vegetated bioswale is a stormwater conveyance system that channels stormwater. This type of buffer system improves water quality by reducing flow velocity and increasing sedimentation, filtering pollutants, and allowing infiltration into the underlying soils.

• A filter strip is a band of vegetation that can be used between a greenhouse and a waterbody. The purpose of the filter strip is to slow runoff from the production area and trap sediment, fertilizers, and pesticides before they reach surface water.

• A constructed wetland is an artificial marsh or swamp for treating wastewater, controlling flood waters, and reducing erosion. In greenhouse production, they can be built to further remove pollutants in the effluent from a retention basin.

Although there are different types of vegetative buffer systems, most work in a similar manner. Runoff containing soluble nutrients and pesticides, and sediments with adsorbed pesticides, enters the buffer. Vegetation in the buffer slow surface flow and sediments drop out. Some water infiltrates into the root zone and subsoil, while the remainder becomes lateral subsurface flow. When the roots of buffer plants grow to sufficient depth, they intercept infiltrated water, taking up the soluble nutrients and pesticides. Pesticides adsorbed to soil particles become trapped in the root zone, and high soil organic matter provides conditions for denitrification and pesticide degradation.

Things to consider before constructing a vegetative buffer.

When planning and designing a vegetative buffer, it is best to consult a licensed engineer or the Natural Resources Conservation Service (NRCS). Buffers need to be designed and constructed to comply with all federal, state, and local laws and regulations.

Plant species that are used in buffers should be selected based on their adaptability and tolerance to site conditions. Check local information sources, such as the NRCS and Cooperative Extension, before making selections. Some points to consider are: cost, growth rate, potential of plant invasiveness if not using native plant species, and the ability to use the buffers for producing secondary crops. Growers who are interested in developing techniques to produce secondary crops in vegetative treatment systems should contact Cooperative Extension and the NRCS for guidance.

Planting should be timed so buffers are established prior to expected runoff. Maintenance of vegetative buffers is necessary to sustain buffer function and effectiveness.

The information above was extracted from a larger document, written by Ventura County Cooperative Extension Farm Advisor, Julie Newman. Please contact us if you would like to read the original document in its entirety.

Ventura County UCCE Staff Research Associate Maren Mochizuki shares current research which hopes to provide an organic method to kill plant pathogens and weed seeds in production agriculture.

Synthetic chemicals to fumigate soil have been used in some production agricultural systems, to kill plant pathogens and weed seed before planting crops.  Here in Ventura County, this is a common practice for strawberry production.  Joji Muramoto, Associate Researcher at UC Santa Cruz and Oleg Daugovish, Ventura County UCCE Farm Advisor and Maren Mochizuki, Ventura County UCCE Staff Research Associate are investigating an organic method to treat soil before planting by creating anaerobic, or oxygen-free, conditions.  Most organisms, including plant pathogens, cannot survive without oxygen.

We incorporated rice bran from the Central Valley into the soil as a carbon source to trigger microbial activity.  To test the applicability within a strawberry production system, we created planting beds topped with plastic mulch.  The beds needed to be well-sealed to ensure no air leaks that could add oxygen.  Using drip irrigation, we added sufficient water to the beds to fill all soil pores, further pushing out any air/oxygen.  Each day we monitor the soil environment with sensors measuring soil water content, temperature, and the level of anaerobic conditions and add more water as needed.  At the end of three weeks, we will evaluate the survival of a significant plant pathogen, Verticillium dahliae.

ASD Sensors

ASD beds