- Author: Krista Rindell
Happy 2016 from the Fruit and Nut Research and Information Center!
We want to take a moment to remind you that the FNRIC website is fully formatted to be compatible with mobile browsing from cell phones and tablets. This includes all of our pages and links, such as the chill calculators, fruit and nut information and the research databases. By being mobile compatible you can access all of our information from anywhere you are be it traveling, in the field or simply away from a computer.
To access our website from your phone or tablet all you need to do is open your favorite browser and type in fruitsandnuts.ucdavis.edu. Once our homepage is loaded you can browse our information and follow the links just as you would from your computer. Below are some screenshots of what you will see when accessing our website from a mobile device.
If you encounter any issues or have questions please email us at firstname.lastname@example.org.
- Author: Janet M. Zalom
The simplest models developed to estimate chill accumulation use a simple count of the number of hours in which the temperature is below 45°F (Chill Hours). However, there is a concern with the chill hour models, particularly under mild winter conditions, such as last year. From the perspective of tree physiology, when cold winter nights (below 45°F) are immediately followed by warm winter days (above 75°F), some of the accumulated chill can be cancelled out, and the Chill Hour model does not account for this. The Dynamic Model was developed to respond to these conditions. It counts chill accumulation (Chill Portions) during hours below a temperature threshold, but then eliminates that accumulation if cold temperatures are followed by warm temperatures within a 24 hour time span.
Regardless of which model you are watching, the current season is chilly, so far. Both Chill Portions and Chill Hours are higher than 5-year averages (tables below). Does this mean we will meet the chilling requirement for your trees? It is too early to say for sure but we are off to a great start!
For excellent references for the chilling requirements of various crops, including variety-specific details, see: Fruit & Nut Crop Chill Portion Requirements by UCCE Orchard Advisor Katherine Pope and the table at the bottom of the webpage: Prune Chilling Prediction Model by UCCE Orchard Advisor Franz Niederholzer.
- Author: Cheryl Reynolds, UC IPM Program
Calculators from the Department of Pesticide Regulation (DPR) that determine the VOC emissions from fumigant and non-fumigant pesticides before application are available to help growers, pest control advisers, and pesticide applicators comply with the regulations. The UC Statewide Integrated Pest Management (IPM) Program provides a link to these calculators from each of the treatment tables in the UC Pest Management Guidelines and click on the Air Quality – Calculate emissions button.
Take steps to reduce VOCs. Avoid emulsifiable concentrate (EC) formulations as they release the highest VOC emissions. Pesticide control advisers and growers can also reduce VOC emissions by employing IPM practices such as using resistant varieties, traps, exclusion, and biological control. When using pesticides, spot-treat and seek low-emission materials. Solid formulations, such as granules or powders, are best.
Check the fact sheet on the DPR web site for the most up-to-date-information on VOC restrictions and regulations.
- Author: Janet M. Zalom
Set for Nov 16 - 19, 2015 on the UC Davis Campus
The UC Fruit & Nut Research & Information Center and UC Cooperative Extension are offering a pomology short course focused on Walnut production: tree biology, orchard management and postharvest quality. This four-day course will be held November 16-19, 2015, on the UC Davis campus. Instruction will be delivered by over thirty UC Farm Advisors, Specialists and Faculty who have been involved for decades in research and extension work in walnut production. They will cover walnut biology and a wide range of topics in orchard management including cultivar selection, irrigation, fertilization, pest and cover crop management and harvesting operations.
The course program allocates time for discussion at the end of every session, quality time with instructors and networking opportunities among participants. Two afternoon field trips to orchards are planned, to complement the lecture/discussion sessions.
The enrollment fee of $1500.00 will cover instruction, course materials, breakfast and lunch, the half-day field trips and an evening social. The class will be held on the UC Davis campus, in the ARC Ballroom, which has largest meeting rooms on the campus. We have reserved this facility because we anticipate a high enrollment for this class and want to comfortably accommodate as many people as possible. This course is intended for growers, students, and professionals working in walnut production. If you are interested, please enroll soon to ensure your place. Attendees will receive a certificate after completing the course.
Online registration and more about the course is available on the UC Fruit & Nut Research & Information Center website: http://fruitsandnuts.ucdavis.edu.
Spider mites, fruit moth and twig borer larvae, aphids, and bark cankers are just a few pests that can wreak havoc on stone fruit trees. With spring well underway and trees in full bloom and beginning to develop fruit, it's time to monitor and take action before these pests get out of hand.
UC IPM teamed up with UC farm advisors to develop a series of how-to videos that can help growers and pest control advisers monitor for pests and damage and determine if and when treatment is needed.
In one video, Sacramento Area IPM Advisor Emily Symmes gives a brief overview of how to monitor for webspinning spider mites. Spider mites build up in stone fruit trees as the weather warms up. Late spring through summer is the ideal time to monitor for mites and their damage, which includes leaf stippling and webbing. If mites build up too much, leaves can drop, fruit may not fully develop, and branches and fruit can be exposed to sunburn.
Shoot strikes, or dead drooping leaf tips, are often seen on young peach and nectarine trees. In a second video, UC Sutter and Yuba County Farm Advisor Janine Hasey explains how to monitor for shoot strikes and how to distinguish the culprits, oriental fruit moth and peach twig borer. Although Oriental fruit moth and peach twig borer can bore into both foliage and fruit, they cause the most devastating damage by feeding on fruit. Early season monitoring and treatment can prevent future fruit loss.
In plum and prune orchards, leaf curl aphids and mealy plum aphids cause leaves to curl and become distorted. Aphids produce honeydew, which can lead to the development of sooty mold, causing fruit to crack and blacken. Aphids are often present when leaves start to grow. In his video, Rick Buchner, UC farm advisor for Tehama County, discusses how to monitor for aphids and explains how to decide when treatment is warranted.
In a final video, UC Sacramento County Farm Advisor Chuck Ingels teaches how to distinguish Phytophthora root and crown rot from bacterial canker. The two diseases are often confused because they both cause bark cankers. Phytophthora root and crown rot is confined to the lower trunk, but when a bacterial canker infection occurs in the tree trunk, the diseases can often be confused. Bacterial canker can be confirmed by cutting away the outer bark and looking for characteristic red flecks on the inner bark. Correct identification of these diseases will help in choosing a management strategy.
You can find all of these how-to videos on the UC IPM video library page. For specific information about managing pests in stone fruits or other crops, see the Pest Management Guidelines. Photos (below) by Jack Kelly Clark.