By Angus Crawford
APAL has updated our Apple and Pear Variety Register that provides growers with a summary of currently available varieties and those in development for Australia.
The aim of the register is to provide an independent overview of the array of apple and pear varieties currently available and in development in Australia. The register enables readers to see the basic information on each variety such as appearance, origin, harvest date, crosses as well as the current marketing arrangements in place.
The register is a collection of information from nurseries, breeders, growers and developers about their varieties and further information can be added.
More often now, the newer pome fruit varieties that are coming through the development pipeline are patented ‘club’ varieties where exclusive growing or selling rights are given to a more limited number of orchards. In effect, this can provide growers better control over the market life and enhance the opportunities for success. When the term ‘club’ is used in the register it is intended as a guide only because some club varieties/brands are well established and others only have the intention of forming a club. Interested growers should seek further information from the variety manager as listed.
Increasingly more varieties are combining disease resistance with good eating quality and attractiveness attributes. Scab (blackspot) resistance is a trait of apples such as Modi® and Kalei as well as some promising untested lines from CIV Italy (Centro Innovazione Varietale) branded ‘Sweet Resistants’ in Australia. There is also overseas interest in scab resistant Opal® and Bonita, which are not listed in this variety register.
The basis of the scab resistance bred into these varieties is based on the Vf gene, which comes from a wild type apple. In some heavy blackspot infestations this disease resistance has broken down, especially where there are certain races of scab – pathotypes 6 and 7 – which can overcome this resistance. ‘Eco-friendly’ claims on apples that have the Vf resistance gene, such as Modi, can be justified because they require less fungicides to control scab.
Red-fleshed apples are being developed for their unique selling point of simply having a red flesh, but they may be marketed as a healthier option too. Non-red flesh apples are naturally high in vitamins, minerals, antioxidants and have a low glycaemic index. The red flesh in red-fleshed apples is caused by extra anthocyanin, which is an antioxidant, so any bonus health claim may be about antioxidants. Red flesh varieties have been in development for at least 25 years but it is only recently that we have started to see these types of apples with good eating quality. Prevar, Lubera and IFORED (International Fruit Obtention) are all organisations working in this space with presences in Australia.
While not published here, we have also developed a register for rootstocks that is available on APAL’s website.
Newer alternative rootstocks are now listed for growers to consider. While rootstocks such as M9 and M26 (M26 being the most sort after rootstock) will still remain dominant for some time, we see that in other countries there is some interest in evaluating alternate rootstocks for commercial situations.
Although M9 and M26 are widely considered ‘almost perfect’ rootstocks, they are still susceptible to a range of diseases, which is major reason why promising rootstocks with similar growth characteristics along with disease resistance traits are being trialled and planted worldwide.
In a recent trip to Italy, I viewed research underway with Dr Nicola Dallabetta looking at rootstocks on different training systems. In particular their focus is on the Cornell-Geneva rootstock series for overcoming replant disease as they lack effective fumigation treatments. In Europe, growers are being challenged by customers to meet increasingly stringent residue standards. As a result, a number of chemical control options are being removed opening up pest and disease gaps that had previously been controlled. Ultimately they hope that they can mitigate many of their problems through new rootstocks and varieties while still increasing production and the high quality standards customers also expect.
The major issue in Italy is apple proliferation disease, followed by woolly aphid, white root rot, apple dieback and replant disease. Apple proliferation does not occur in Australia but is listed as a priority exotic plant pest that we hope we don’t have to deal with here.
In Australia we can have severe problems with woolly aphid, phytophthora and other root rots, as well as apple replant disease. Burr knots are emerging as a more common disorder of Australian orchards where, if left untreated, they will leave entry points for diseases, cause losses in production and often tree death. The general characteristics of the Cornell-Geneva rootstocks are that they are replant tolerant, woolly aphid resistant, have low suckering and are cleaner with fewer burr knots.
For these reasons growers should consider trialling small areas of these commercially available lines in their orchards. From observation these rootstocks should be planted on at least a bi-axis system to better control tree vigour. Normal practices of soil preparation, deep ripping and fumigation are still necessary.