Major pests and diseases The pest that is considered the major constraint to the trade of Australian Lychees is the Queensland fruit fly, Bactrocera tryoni (Q fly).
Lychee farmers have disputed this, as Q fly has never been recorded to cause economic damage in orchards, so consequently farmers do not take any control measures for them.
Due to a few reports in the literature, lychees were regarded as very poor hosts to Q flies, however, they have never been detected in fresh fruit with an unbroken skin.
Currently lychees are being sent under an unbroken skin protocol, ICA 13, to Victoria and South Australia. Both of these States have strict quarantine requirements to maintain their fruit fly area freedom status.
Since 1998 we estimate that 5755 tonnes of lychees, consisting of 1,151,000 cartons have entered Victorian and South Australian markets under the ICA 13 protocol without one single fruit fly detection.
Recent host testing has shown that fresh lychees are not a host to the Queensland fruit fly. (Leach pers com.)
The only time a few larvae will emerge is if the lychee fruit is oviposited when it is in a state of decay. Some researchers believe that there are compounds in fresh lychees that inhibit Q fly larvae. It is only when the fruit is in a state of decay and these compounds are breaking down, that Q fly larvae can survive. The sparse records of Q fly in lychees show that they have been found on decayed fruit that has dropped from the tree or as rotting fruit on the tree. Leach pers com.
As decaying fruit is not packed for sale, the only lychees that are sent to market are not hosts for Q fly.
The following pests are considered economic pests of lychee production, however, are not generally considered as quarantine risks. This is due to their preference of either damaging leaves, flowers, immature fruit or that they are wide spread in other countries, cannot survive in cool temperate climates and/or the packed fruit with an unbroken skin is not a vector for their spread.
- Winged vertebrate pests of Flying Foxes (Pteropus spp) and parrots like Rainbow Lorikeets (Trichoglossus haematodus) are considered the most serious production pests of lychees, causing significant losses of mature fruit. Netting, lights, electric grids and scarers are used with various successes. Throw over nets are only partially effective as they can chew through the nets, crawl under them or enter through any small holes. The only proven method is complete exclusion netting however due to a range of problems and the high cost it is not used by the majority of growers because it is uneconomic.
- Macadamia Nut borer (Cryptophlebia ombrodelta). They prefer to feed on immature fruit that are shed from the tree before the fruit matures.
- Leaf and flower eating caterpillars (various Lepidoptera spp). Feed on leaves and flowers however do not effect fruit.
- Swarming beetles - Monolepta australis, Rhyparida spp. Feed on leaves and flowers however do not effect fruit.
- Lychee erinose mite (Aceria litchi), usually affects the leaves however can damage flowers and young fruit. This mite is specific to lychees and will not effect other crops.
- Fruitspotting bugs (Amblypelta nitida; Amblypelta lutescens). They prefer to feed on green fruit and most fruitspotting bugs migrate into the trees just after fruitset.
- Yellow peach moth (Conogethes punctiferalis). Eggs are laid on the developing fruit or near the growing point. These fruit tend to be shed by the tree and do not mature.
- Fruit piercing moths (Eudocima salaminia; E. fullonia; E. materna). Feed on the aril however they do not reproduce on lychees so they are not a vector for their spread.
Production Methods Currently there are no defined single production standards for pest control, fertilising, pruning, weed control and irrigation.
Around 20% of the industry is working with ALGA, the Queensland Department of Primary Industries (QDPI) and Horticulture Australia Ltd (HAL) with the 'Unlocking Lychee Research' project to establish best practice in all of these areas to establish them as industry benchmark standards.