The following presentation was given at the ATGA conference in Launceston in 2014.
Ainsley_Seago_truffles_pests_2014
Threat from Field Mice and Foxes PDF, correspondence about field mice and fox damages.
Pests and diseases – trees
Young trees are susceptible to several pests, in particular African black beetle, weevils, spring beetles, wingless grasshoppers and snails.
African black beetle damage is mainly caused by the adult beetles and occurs at or just below the soil surface, effectively ringbarking the tree. The impact can be minimised by leaving the area bare for as long as possible, ripping along the planting rows, removing any grasses, especially kikuyu, and with the use of grow guards that are set about 5cm into the soil around the tree. This prevents the beetle accessing the new tree stem. Searching for and removing any larvae or beetles from the planting soil, followed by use of a tree guard can be very effective.
Weevils, beetles and grasshoppers can decimate the foliage of young trees and larvae can chew roots leading to stunting and stressed trees. Monitoring numbers in the field prior to planting can give an indication of the problem and informed management options.
Birds such as ducks, guinea fowl and chickens at a stocking rate of 50 per hectare can be very effective at beetle control and have the added benefit of controlling other insect and snail pests. Guinea fowl and chickens do dig when they dust-bath which may not be beneficial for the developing truffles, however ducks do not tend to do this.
Snails may chew young leaves of seedlings and are more likely to damage hazelnut seedlings than oak seedlings. Trapping and physical removal of snails is likely to be effective at this stage in the orchard life cycle. Maintaining weed-free areas around new trees will also minimise damage. Small pointed snails can interfere with sprinklers. Snails and slugs are potentially a problem for the growing truffle as discussed below.
Mature trees are less susceptible to damage by pests, however in some areas fruit tree borers can severely damage trees. These are best managed by completely removing any affected trees and burning the wood.
Oak powdery mildew (Erysiphe alphitoides) is often observed on trees in spring. This mildew is a different fungus to that seen in vineyards (grapevine powdery mildew – Uncinula necator) and there is no cross-infection between vines and trees. Warm damp spring conditions favour formation of mildews in many horticultural crops. Spring infections with powdery mildew can be severe in trees already stressed for other reasons, such as mineral deficiency or water-logging. Late summer and autumn infections often occur on senescing leaves and are unlikely to be a problem. In general, no treatment is required for powdery mildew.
Pests and diseases – truffles
Snails and slugs appear to be the major pests of growing truffles, followed by springtails (Collembola spp.), fungus gnats and truffle beetles. Encouraging truffles to form below the soil surface appears to be the single most effective defence against all pests at present.
Mammals including small marsupials, rabbits and pigs can be troublesome by digging up both ripe and unripe truffles. Good fencing will prevent most of these animals entering the orchard. If feral pigs are present, electric fencing will be needed as pigs are particularly fond of truffles. The presence of pigs should be reported to the local DAFWA office. Kangaroos may come into the truffle orchard to eat nuts and acorns but are not known to eat the truffles. They can cause damage to fences so monitoring their activity is important.