Australian Truffle Pest & Disease Newsletter

Eastern states’ road trip July 2018

To get an idea of where truffle growers are at as far as damage to truffles is concerned and take the opportunity to give an update on the project especially for those growers not intending to go to the September 2018 National Truffle Conference, Stewart spent two weeks in NSW, Victoria and Tasmania in July this year.

Truffle Damage

Where possible, Stewart tagged along as truffles were being harvested. The aims were to see if there were any new pests, which can only be identified confidently during harvest. The other main aim was to see whether damage was related to depth of truffles, as is the case for a study in WA where we found exposed and shallow truffles have more damage than truffles that form greater than 25mm. Stewart visited three orchards near Canberra, two in central NSW, two in Victoria and two in Tasmania.

The photos below indicate the activities undertaken and some of the main pests found.

slug eggs and damage on truffle
Slugs leave their calling signs, eggs and feeding damage
slaters in a severely damaged truffle
Slaters demolished this truffle
Portuguese millipede in truffle
Portuguese millipede
truffle with small holes
Damage that looks like that caused by Australian truffle beetle, alhtough no beetles were observed.

Across the nine truffle orchards visited, damage by invertebrates as direct feeding loss by weight was less than 6%, but the proportion of truffles with any level of invertebrate damage varied from 26% to 59%. When such a high proportion of truffles is damaged at some level, a reasonable amount of time is spent in the grading room assessing and trimming truffles. As well as the reduced price due to downgrading there is also an extra cost of time to trim during this already busy part of the season.

In some of these orchards, limited bran-baited tile monitoring for invertebrates indicated their abundance was generally consistent with the levels of damage.

As far as identifying invertebrate pests that do not commonly damage truffles is concerned, the only possible culprit is millipedes. Unfortunately, this occurred in orchards where regular monitoring had not taken place, so this conclusion remains somewhat speculative.

As well as damage by invertebrates affecting yield, rot in truffles was recorded as significant in two orchards at 23 % and 33% loss. The cause for this was not apparent, especially given the dry season in the east during 2018.

person and dog harvesting truffles
Ian Woodhouse checking truffles for damage during a harvest at his orchard in Victoria
freshly harvested truffles sorted into depths they were harvested from.
Freshly harvested truffles sorted into depths they were harvested from. Most truffles in this harvest were 'deep'.

Updates on the pest and disease project

Stewart gave a talk on the project activities at the following locations - Sutton, Bathurst, Ballarat and Deloraine. You can read that presentation here. Anne Mitchell attended a truffle-grading workshop in Victoria in July where she also presented an update on the project.