UCCE Ventura County- Blogs
Avocado Lace Bug Talk
Growers Invited to Avocado Lace Bug Presentation
On May 14 at 12:30 p.m., Paloma Dadlani — a graduate student under Dr. Mark Hoddle who has been spearheading avocado lace bug research funded by the California Avocado Commission — will deliver her master's thesis defense seminar. Interested California avocado growers can view the thesis defense online or attend in person at the UC Riverside Entomology Building located at 165 Citrus Drive, Riverside, CA.
The thesis covers the following topics:
- Effects of temperature on developmental and reproductive biology, and degree-day models. This work helps predict development times in the field and will inform growers on possible levels of control from hot weather events.
- Two years of population phenology data from four commercial Hass avocado orchards in San Diego County, and surveys for ALB on non-Hass avocados like GEM, Lamb Hass, Bacon, and Fuerte. Natural enemy surveys are included, and sticky card captures to monitor adult dispersal by flight.
- Updated molecular analyses on ALB populations in San Diego county (the original 2004 population in Chula Vista and National City are still there), including comparisons to the "aggressive" populations in northern San Diego County, Riverside, Los Angeles, and Santa Barbara Counties and the extremely damaging populations in Hawaii.
avocado lace bug damage
avocado lace bug 1
Spray Meeting
Register Here: https://surveys.ucanr.edu/survey.cfm?surveynumber=42797
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How Much Fruit is Up there?
Old crop, new crop. What's up there in the trees? Are they big enough to sell? Is there a good set for next year? These are questions every avocado grower has every year, and often all year long. What is up there in the trees is confounded by what is called the "Avocado Illusion".
And boy was I reminded of the issue the other day when harvesting a GEM planting density trial. You don't see GEMs, you feel them, sense them being somewhere near your hand. There's a mass that's different from all the leaves near your hand, and you reach for it with your clipper and by golly you got a live one. But how many have you missed? You really need to search.
In a Science Magazine Letters to the Editor in Dec 1990, Paul Sandorff commented on a book written by Maurice Hershenson called The Moon Illusion. In the book Hershenson described the illusion of why the moon seemed so much larger when it was on the horizon than when it rose to its zenith on the same night. http://science.sciencemag.org/content/250/4988/1646.1
Sandorff said that this illusion applied to avocados since it was so hard to gauge the size of avocados when they were in the tops of the tree canopy. It is the surrounding environment that puts a context to size according to this theory of illusion.
Hershenson added to this observation in the March 1991 Science letters section with the comment that the leaves surrounding the fruit changes our depth perception and so changes our idea of the fruit size.
A further addendum to the avocado illusion theory is that since the fruit are the same color as the leaves (they are both dark green and the fruit unlike most other fruit continues to photosynthesize), it is hard to actually make out the fruit. You can be looking right at the fruit and not see it, confusing it with a leaf.
This illusion makes for difficult fruit estimation. To compensate for this illusion, I will eye the canopy in quadrants, counting the number of fruit, then arbitrarily doubling that total number. It usually gives a pretty close number to the real number of fruit that are in the tree.
By the way, with all the low down fruit in the skirt and with the wet winter, there were a heck of a lot of snails in the canopy dining on fruit.
Photo:
Can you count the number of fruit in this Hass canopy?
Photo: a mess of GEM fruit revealed hiding in the skirt.
GEM fruit on skirt