The redbay ambrosia beetle, Xyleborus glabratus, and its fungal symbiont, Raffaelea lauricola (Rl), were introduced into Port Wentworth, Georgia, USA, in infested wood packing material from Asia during 2002. This insect-disease complex, commonly called laurel wilt (LW), affects trees in the Lauraceae family and spreads through natural areas by redbay ambrosia beetle movement and anthropogenic movement of infested wood products (e.g., firewood, wood-turners wood, and BBQ smoke-wood). Plant hosts of the redbay ambrosia beetle-Rl complex include at least ten native lauraceous woody species (e.g., redbay [Persea borbonia] and swamp- bay [P. palustris]) in Florida, as well as non-native species such as camphor (Cinnamomum camphora), avocado (P. americana), and potentially California bay (Umbellularia californica). By February 2010, redbay ambrosia beetles were detected in a natural area 21 miles (33.7 km) north of the south Florida avocado production area (125 sq. miles; 324 sq. km) in Miami-Dade County. In 2011, the first confirmed swampbay tree to succumb to LW was documented in this natural area, and by 2012 LW was detected in a commercial avocado grove in Homestead, Florida.

Now everything we know about this disease that affects avocados and other laurel relatives is at one website - articles, videos, webinars, maps.  Check it out: https://trec.ifas.ufl.edu/faculty/dr-crane-lw-ab-website/lw-ab/

If you missed the recent UC/CAS/CAC grower meeting on cooling avocado trees or just want to review the enormous amount of information or just want to wander other grower's orchards, Here is the video of the presentations:

Mitigating Heat

This article was first posted in July of 2020 when it wasn't clear what this leaf roller/leaf miner was going to do.  In the last couple of weeks I have heard from two PCAs from Ventura saying that they are having to spray for it.  So, it is back and it is probabl6y going to hang around for a while. It does not seem to feed on fruit.  It causes damage to leaves but it doesn't seem to be significant on mature trees.  On a newly planted tree, it can defoliate it, so it should not be neglected.  Read the history below.

A new pest for avocado? Old pest? How much damage will it do? Don't know yet.

Tracy Ellis, the San Diego County Ag Commissioner Entomologist has partially identified what appeared to be two pest and a parasitoid, as only one pest and a beneficial that is doing it's duty going after the pest.

The insect determination has come back for both larvae (one a leaf miner and one a leaf roller) as the same insect! It has been determined to be C-rated gracillariid miner Caloptilia sp. (Lepidoptera: Gracillariidae) at this time. An image of the adult moth is not yet available.

Apparently, the larval stage transitions from a miner to a roller, in what's called hyper-metamorphosis. Starting as a miner and abandoning the mine to roll the leaf. CDFA scientist Marc Epstein is taking a closer look at this insect . Marc does not know if it is a local insect that adapted to avocados or is an import, as many in this family have not been studied or sequenced.

The leaf roller/folder has appeared down in San Diego and Santa Barbara. It's not clear whether it will be a pest of the fruit at this time.

The results for the parasite came back as Hymenoptera.  That too needs greater study.

Above is a photo of both insect stages. They can be found together in the same habitat.

The damage from the leaf miner generally looks like this

 And miner looks like this

The damage from the leafroller looks like this:

Larval leafroller with the parasite on it.

And the parasite , once it grows up from being a maggot, looks like this

It's still not clear what damage this might do.  Maybe nothing significant.  Maybe this is an aberration only for this year.  Stay tuned.

A recent publication points out the need for identifying and improving habitat for avocado pollinators.

The role of insect pollinators in avocado production: A global review

Keira Dymond, Juan L. Celis-Diez, Simon G. Potts, Brad G. Howlett, Bryony K. Willcox, Michael P. D. Garratt

Insect pollination increases the yield and quality of many crops and therefore, understanding the role of insect pollinators in crop production is necessary to sustainably increase yields. Avocado Persea americana benefits from insect pollination, however, a better understanding of the role of pollinators and their contribution to the production of this globally important crop is needed. In this study, we carried out a systematic literature review and meta-analysis of studies investigating the pollination ecology of avocado to answer the following questions: (a) Are there any research gaps in terms of geographic location or scientific focus? (b) What is the effect of insect pollinators on avocado pollination and production? (c) Which pollinators are the most abundant and effective and how does this vary across location? (d) How can insect pollination be improved for higher yields? (e) What are the current evidence gaps and what should be the focus of future research? Research from many regions of the globe has been published, however, results showed that there is limited information from key avocado producing countries such as Mexico and the Dominican Republic. In most studies, insects were shown to contribute greatly to pollination, fruit set and yield. Honeybees Apis mellifera were important pollinators in many regions due to their efficiency and high abundance, however, many wild pollinators also visited avocado flowers and were the most frequent visitors in over 50% of studies. This study also highlighted the effectiveness of stingless bees (Meliponini) and blow flies (Calliphoridae) as avocado pollinators although, for the majority of flower visitors, there is a lack of data on pollinator efficiency. For optimal yields, growers should ensure a sufficient abundance of pollinators in their orchards either through increasing honeybee hive density or, for a more sustainable approach, by managing wild pollinators through practices that protect or promote natural habitat.

Read the full article: https://onlinelibrary.wiley.com/doi/full/10.1111/jen.12869

Hover fly visiting an avocado flower in the South-West of Western Australia (©2021 DPIRD)