ATHERTON OAK - PART II

SCIENTIFIC NAME: Athertonia diversifolia
FAMILY: Proteaceae

This is the second and final part of Bernard Murawski's Paper on the Atherton Nut.

Athertonia diversifolia - The Queen of Nuts

Pests and Diseases
The Atherton Oak has few major pests and diseases (Irvine, 1985). The low number of pests may be due to the relatively high number of spiders that tend to live in the Atherton Oak's canopy. A number of insect pests have been seen chewing on the leaves and flowers but only negligible damage is done to the tree (Irvine, 1985; Costin, 1998).

This may be true at present with only a relatively small number of plantings. The situation may change as the number of plantings increases (Fletcher, 1998). Kernels are attacked by fungi, but this may be a secondary infection following insect damage (Irvine, 1985).

The pests and diseases of the Atherton Oak's close relative, the macadamia, may offer some insight into the potential problems that may affect the tree in cultivation. Growers need to be familiar with the pest and the symptoms. For insects, their egg, larval, and adult stages need to be identifiable as well as their feeding habits and the periods when they are most active.

Macadamia Flower Caterpillar
The macadamia flower caterpillar is a pest solely of members of the Proteaceae family and is a major pest to the macadamia. The larvae feed on the exterior of the flower buds with most of the damage being caused by the mature larvae. The larvae create a silk web to which the spent flower buds and faeces attach.

Large economic losses can occur if the infestations are severe, but little economic loss will occur with low to medium infestations Most infestations occur during the main flowering period, so monitoring for eggs and larvae should start at the commencement of flowering.

Monolepta Beetle
The Monolepta beetle swarms and can cause considerable damage to orchards in only two to three days if not checked. The insects seem to favour the flowers and young fruit of the macadamia but when these are not available, will target the foliage.

Macadamia Nutborer and Macadamia Husk Spot
Both these pests can cause severe losses; the macadamia husk spot by limiting oil accumulation in the nut. Both have the potential to produce premature nut fall. Owing to the different make up of the Atherton Oak's nut with a fleshy outer coat as opposed to the macadamias hard husk, these pests may not be a problem for the Atherton Oak.

Flower Thrips
Flower thrips attack the flower buds, new growth and young fruit of the macadamia. This stops the growth of the buds and leaves, which become distorted. Thrips prefer a drier climate and are only a problem in drier areas or during dry climatic conditions.

Fruit Spotting Bug
These are a major pest of the macadamia and reduce yield and quality of the nuts by piercing the husk and damaging the kernel. This usually causes premature nut drop but nuts may stay attacked to the tree with the nut being ruined. Losses are greater when the nuts are young and have a soft shell.

Latania Scale
Latania scale (Hemiberlesia lataniaee) feeds on the fruit, leaves, branches and stems of the macadamia by sucking the sap from the plant. In severe infestations this can cause the plant to become unthrifty. The numbers of the scale usually increase to problem proportions as a result of the overuse of chemical sprays destroying their natural enemies. Latania scale may be more of a problem in the relatively milder conditions of northern NSW than in Queensland.

Macadamia Leafminer
The macadamia leaf miner causes damage to the leaves by burrowing under the upper leaf surface and feeding there. The insect feeds exclusively on new foliage and so is predominantly a pest of young trees and nursery stock.

Macadamia Twig Girdler
The macadamia twig girdler feeds on the dermal layers of the stems under a silk web that is studded with the insect's excreta·. The feeding insect may lead to severely reduced growth of the tree, with a bunched growth habit forming from the affected stems. Damage is most prevalent during summer and autumn.

Macadamia Felted Coccid
The macadamia felted coccid is a problem on the above-ground parts of the tree. It feeds on the plant's sap and distorts and stunts new growth. Severe infestations cause dieback, reducing yields and even killing the tree.

Armillaria Root Rot
Armillaria root rot (Armillaria luteobubalina) infests the roots, with affected trees slowly declining or suddenly collapsing. The fungus is a major problem on newly-cleared land and lives on the stumps and roots of the cleared trees.

The black, cordlike fungal threads infect the surface of the major roots, with honey-coloured mushrooms occasionally forming at the base of the tree after wet, winter weather. Newly-cleared land would need to have the roots and stumps removed before planting young Atherton Oaks, with fumigation of the soil also necessary.

Trunk Canker
Trunk canker (Phytophthora cinnamomi) can be a devastating disease, especially in the early years of growth. The fungi attack the roots, causing them to turn brown, decay and die back. In younger trees the stem shows girdling with mauve or tan-coloured tissue underneath the bark. In older trees the base of the tree has discoloured bark and may exude a red gum.

The canker may extend up the tree to the lower branches, with trees affected by the fungus often producing a heavy set of fruit in the final stages of the disease. To help prevent the disease, it is important to avoid wounding the base of the tree, and to plant in well-drained soils.

Mammals
The nuts of the Atherton Oak are at risk of predation from rats and wild pigs, primarily while they lie on the ground. The young trees may be susceptible to attack from hares and wallabies.

Rats
Native rats, including the white tailed rat (Uromys caudimaculatus, Goldberg, 1996) and the introduced black rat (Rattus rattus), are the main predators of Atherton nuts and can cause considerable losses.

In an orchard situation, the black rat may be the major problem, as is the case in macadamia orchards (O'Hare, et al., 1996) Control would centre around limiting hiding and breeding places for the rats by removing such areas of refuge as long grass. Limiting the quantity of nuts left on the ground may limit the build-up of population numbers.

Feral Pigs
Feral pigs may also be a problem and may cause considerable losses to an orchard as is the case with some macadamia farms (O'Hare et al., 1996). The use of electric fences may be a deterrent to the pigs.

Hares and Wallabies
Hares remove the bark from the trunk and lower branches and wallabies may browse on the new foliage growth of the young trees. Some protection may be given to the young trees by placing a plastic sleeve over the trunk or wrapping it with sisalation. The musky rat-kangaroo (Hypsiprymnodon moschatus) is also a significant predator of the nuts (Cooper and Cooper, 1994).

Market Analysis
The key to exposure in the marketplace is large volumes of a product (Kermond, 1998). The small volumes of Atherton nuts produced would be a major problem in the early stages of the industry. This is especially true due to the limited storage times of the nuts.

Sourcing a sufficient amount of product may also be a problem at the moment due to the limited number of growers at present. Costin (1998) believes that there are only around 10-20 growers who have only a small number of trees on their properties. They are reluctant to grow any more Atherton Oak trees until there are clear signs that the industry will be viable and their investment will produce returns.

Kermond (1998) commented that the word 'Oak' may be a negative attribute for marketing of an 'Australian' product, as the word 'Oak' is associated with overseas trees.

Market segment
Producers could supply two main segments; the food service industry (restaurants) and the retail segment (Kermond, 1998).

Food Service Sector
Consumers have a low awareness and confidence of the Atherton nut. Hence, if it were prepared and presented by chefs with a knowledge of the product, this may be an advantage. This would limit bad experiences with consumers and may be a more cost effective option to train chefs than to educate the end-users (Phelps, 1997).

Restaurants that specialise in bush tucker foods would be the main buyers of the nuts (Kermond, 1998). The restaurants could be approached by the supply of samples of the product along with written material describing the product (Kermond, 1998).

Retail Sector
The benefit of the retail sector is that it can provide exposure of the nut in the market. This is critical in the introductory stage of the product life-cycle to increase awareness and subsequently stimulate demand (Phelps, 1997).

Very small 'boutique' manufacturers would be the only manufacturers interested in working with small volumes of product (Kermond, 1998). These currently produce such lines as wattle seed cookies.

Positioning
The lower fat content is a positive feature of the nut. Consumers are conscious of the amount of fat in their foods, so positioning the nut as a low-fat nut may be of major importance for consumer acceptance.

Export Market
There is a strong interest in Australian bushfoods in Europe, with the potential to outstrip current supply levels just to conduct market trials (Phelps, 1997). The initial low quantities of the product would eliminate any notion of exporting for some time.

Domestic Market
The domestic Australian market is very small when compared with other countries, but knowledge of Australian products is high (Phelps, 1997). Owing to the small quantities of nut that would be available in the first stages of the industry, it would only be possible to supply the Australian market, at first. This would allow the industry to consolidate itself and develop the market. Then as supplies and expertise increase, other markets could then be developed.

Final Product
The product would be suitable for roasting (Sankowsky, 1998) or cooking in oil (Mason, 1998). The nut could be mixed with other food products (such as chocolate) to form a snack food, which would also have the effect of lowering its relative price and/or extend limited supplies (Phelps, 1997). The low keeping-qualities of the fresh nut would probably limit its suitability to be used on the fresh market.

References
The author is grateful for the assistance rendered by members of the Atherton Nut Industry.

Cooper, W. and Cooper, W.T. (1994). Fruits of the Rainforest. A Guide to Fruits in Australian Tropical Rainforests. RD Press, Australia.

Fletcher, R. (1998). Personal Communication.

Goldberg, J. (1996). An Investigation into Seed Predation and Caching in a Tropical Rainforest Rodent, Uromys caudimaculatus, the White Tailed Rat. James Cook University Thesis.

Irvine, A.K. (1985) Commercial prospects for edible nuts of Athertonia diversifolia and Elaeocarpus bancroftii in The Food Potential of Seeds from Australian Native Plants. (Jones, G.P. Ed.) Deakin University Press.

Kermond, P. (1998). Personal Communication.

Mason, R. (1998). Personal Communication.

O'Hare, P., Waite, G. and Mayers, P. (1996). Crop Protection. In The Macadamia. From Seed to the Supermarket. (Kermond, P. and Baumgard, B. Ed.).

Phelps, D. G. (1997). 'Feasibility of a Sustainable Bushfood Industry in Western Queensland'. Rural Ind. Development Corp. Sydney. (1998). Personal Communication.

Sankowsky, G. (1998). Personal Communication.

Taylor, R. (1998). Personal Communication.

Wriglye, J. W. and Fagg, M. (1990). Australian Native Plants. Propagation, Cultivation and Use in Landscaping. Angus and Robinson. Sydney.

Bernard Murawski

DATE: May 1999

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