UCCE Ventura County- Blogs
Microirrigation Clogging Troubleshooting Guide
Microirrigation systems include microsprinklers for tree crops, drip emitters for trees, vines, and some row crops, and drip tape for row and field crops. Microirrigation systems apply water to the soil through emitters that are installed along drip lines and contain very small flow passages. Microirrigation systems can apply water and fertilizers more uniformly than other irrigation methods. This uniformity results in potentially higher yields, higher revenue, and reduced irrigation operating costs.
Uniformity, a performance characteristic of irrigation systems, is a measure of the evenness of the applied water throughout the irrigation system. Distribution uniformity (DU), sometimes called emission uniformity (EU), is an index that describes how evenly or uniformly water is applied throughout the field. A uniformity of 100% means the same amount of water was applied everywhere. Unfortunately, all irrigation systems apply water at a uniformity of less than 100%, and thus some parts of a field receive more water than others. Field evaluations have shown that microirrigation systems have the potential for higher uniformity than other irrigation methods. However, clogging reduces the uniformity of applied water in microirrigation systems, thus increasing the relative differences in applied water throughout a field.
The small flow passages in the emitters and microsprinklers make microirrigation systems highly susceptible to clogging. Clogging reduces the uniformity of the applied water and decreases the amount of applied water. Clogging also decreases the amount of salt leaching around the lateral line in saline soils.
The objective of this web site is to provide information to irrigators about the causes of clogging and the methods for preventing or correcting clogging problems in microirrigation systems. Among the topics covered are the sources of clogging, chlorination, preventing chemical precipitation, filtration, flushing, and monitoring microirrigation systems.
This web site is divided into sections to allow the users to more quickly access the information they want. For example, if you already know you have a clogging problem and you want to solve it, go to the section Solutions to Existing Clogging Problems - "I have a problem and I want to solve it".
https://micromaintain.ucanr.edu/
avocado irrigation 2
A New Topics in Subtropics Newsletter!!!
Hot off the internet, a new edition of Topics in Subtropics, articles from UC subtropical horticulture folks
Topics in Subtropics Volume 25 Spring 2024
Jul 9, 2024
Fatemeh Khodadadi, Editor
Topics in this issue:
- Effectiveness of Asian citrus psyllid management in huanglongbing treatment zones in residential Southern California
- Managed honeybees in a wet year
- Threats to citrus orchards in California by synergistic effects of dry root rot and phytophthora root and crown rot
- Microbial Safety in Avocado Farms
- How Much Fruit is Up there?
- Tiny Troublemakers: How Geminiviruses are affecting California's Crops
- Citrus Leprosis Disease – Staying alert on potential threat to California's citrus industry
Download (3,620KB PDF)
https://ceventura.ucanr.edu/Com_Ag/Subtropical/
AND THERE"S LOTS MORE TO READ FROM THE ARCHIVES
https://ceventura.ucanr.edu/Com_Ag/Subtropical/?newsletterlist=3197
topics in sub masthead
Ants and Mealybugs?
Managing citrus mealybug – does ant control help?
Sandipa Gautam, Sanjeev Dhungana, and David Haviland
UC Co-operative Extension
Starting 2019/20 season, pest control advisors started noticing citrus mealybug infestations in multiple citrus varieties that continued to increase in acreage in the San Joaquin Valley. Although present in the citrus systems, mealybugs were considered to be a minor pest and kept well under check by natural enemies until recently.
What are mealybugs?
Mealybugs are soft, oval, flat, distinctly segmented insects whose body is covered in white mealy wax. Citrus mealybug, Planococcus citri is the most common species associated with citrus. Females lay ~600 eggs in egg sacs loosely held by white cottony flint. Crawlers are yellowish, and can move or be carried by ants, birds, or the wind to start new infestations. Crawlers feed by sucking sap using straw-like stylets and soon develop a waxy covering (Fig. 1C). Like California red scale, females molt and stay as third instars until mated by a male. Males go through a pupal stage and emerge as adults with wings that fly to seek a mate.
Mealybugs prefer the inside canopy of the tree and can be found under dense leaves, between clusters of fruits, or in other cryptic places where they can be difficult to find, especially when the population is low. As the season progresses and the tree flushes, blooms, and fruit develops, mealybugs move to the parts of the tree where nutrients flow. Ongoing research on seasonal phenology suggest that there are 5-6 generations in the San Joaquin Valley. The first generation starts from overwintering adult/egg populations in late March/early April. The second-generation crawlers/nymphs move to fruit in June/July. The remaining generations each year primarily feed and multiply on the fruit.
Mealybugs produce nutrient rich honeydew that is an attractive food source for ants. Ants have been reported to defend insect colonies from predators and parasitoids. In an early infestation, ant trails can be used as an indicator to locate mealybug infestations or other sap sucking pests. Managing sugar feeding ants in citrus orchards has shown increased biocontrol of sap sucking insects. It is plausible that loss of chlorpyrifos as an ant control tool may have aggravated ants thereby aiding to increase mealybug pressure in recent years.
As mealybugs have become a reoccurring pest in citrus orchards, University of California researchers-initiated studies to work towards developing strategies to manage this pest. Research funded by Citrus Research Board and led by Gautam lab is investigating biology, field ecology, and management of mealybugs. During field visits, our observations have shown that various ant species of were present throughout the growing season attending mealybug colonies.
Does managing ant help suppress mealybug?
UC researchers have documented that managing sugar feeding ants increases biocontrol, thereby reducing the pest pressure of sap sucking insects. When ant densities are were reduced >90%, there was ~90% less mealybug on twigs and complete elimination of mealybug was reported from fruit. However, managing ants has been a challenge since the use of chlorpyrifos was banned. To address this need, UC researchers have worked to develop and test different types of hydrogel beads for delivering insecticide products to sugar-feeding species of ants.
Research led by David Haviland has focused on the experimental use of commercially-available polyacrylamide hydrogel beads for large field-scale applications. In 2023 a large-scale field trial was conducted in a 20-acre grapefruit block in Sanger, California. Two applications of hydrogel beads laced with insecticides were made on Aug 2 and August 30, 2023. Post-treatment evaluations for ant density were done on 24 trees/plot by counting the number of ants that passed through a graft union for 15 secs weekly for 4 weeks after each application. The effects of ant suppression on mealybug densities was evaluated in October 2023 by counting the number of fruits infested with mealybugs (presence/absence) on 30 fruits from the inside canopy. Insecticide treatments had variable results on ant density, with lowest ant density consistently found in plots treated with thiamethoxam. Similarly, plots treated with thiamethoxam had the lowest populations of mealybugs.
There's a lot more to this story:
https://ceventura.ucanr.edu/Com_Ag/Subtropical/?newsletteritem=100493
mealybug stages
Mitigating Heat Damage in the Orchard
It's hot and many trees need help in the heat. There's several ways you an help, however many require prior preparation:
?Successful Irrigation is crucial for cooling, both unser-canopy and over-canopy Using the Irrigation systems strategically will achieve best results ?
Mulching tree berms, also improves soil and tree health ?
Monitoring – Soil moisture and air temperatures ?
The use of Protectants(reflectants) products can be used to alleviate the stress of heat, usually provides a few degrees relief ?. Antitranspirants can make it worse by shutting down stoma and reducing cooling transpiration
Cover cropping and hedgerows increase humidity and evaporative cooling.
Watch a video produced by the CA Avocado Society for what can be done in preparation and now:
https://www.youtube.com/watch?v=E7EWU0tAMVY
heat damage to new avocado
Citricola Scale in the Big Valley
Sandipa Gautam, Area Citrus IPM Advisor serving Kern, Tulare, Fresno, and Madera counties has been maintaining a web page on the Lindcove Website Citrus IPM - Lindcove Research and Extension Center (ucanr.edu). Within this page, she writes a blog on pest issues that are problem for growers in the SJV region. For subscribing, click https://ucanr.edu/blogs/IPMBlog/ and enter your email address. You will receive an email to confirm subscription, follow the instructions to complete subscription. Every time a post is made you will receive and email notification. This page also hosts pest memos of this season and archives from the previous season along with links to Citrus related extension posts, newsletters.
Within the Citrus IPM tab, you will also find Degree Days, which is regularly updated for California red scale for four counties in the SJV. If you are in Ventura county or other citrus growing counties (not in the valley) and California red scale is a pest you manage and are interested in Degree Day calculation and predictions, please contact sangautam@Ucanr.edu .
If you would like to receive emails on pest memos/other events, please send an email to sangautam@ucanr.edu to be added to her email list.
citricola scale blog