Valencian technicians provide solutions for the shortcomings of the Australian orange, crop M7.

Researchers and technicians that have worked over the last two years to solve some shortcomings in the new M7 orange crop insist that those difficulties are practically solved; in fact, this year there have been much fewer occurrences. Citrus fruit growers that have opted for this promising patented variety agree: they are increasingly more interested in exchanging experiences to improve results to the maximum.

With the intention of promoting the dissemination and exchange of technical know-how, Compañía de Variedades Vegetales Protegidas A.I.E (CVVP), which manages this variety and others (Nadorcott and Leanri mandarins and the Summer Prim lemon), organised a meeting of M7 producers with technicians experienced in its cultivation, including visits to production farms located in the Guadalquivir valley and in Valencia.

This is a practice that is very useful and should extend, undoubtedly, to other varieties and cultivations; all the while there are more or less generalised problems and there are different ways of addressing or treating them; because by simply showing what is done or what is not done there is the possibility of contrasting excesses or shortages and the best way to learn is in the field in order to act accordingly.

Carlos Mesejo, professor of the Agro-forestry Institute of the Polytechnic University of Valencia, and Camilo Garcés, citrus fruit technician and producer of M7, focused on the main problems which, in principle, had worried, at least until now, the farmers of this Australian variety: Cracked branches, split fruit, occasionally bruised peel due to the wind, and some size deficiencies.

Professor Mesejo warned that “no variety comes with an instruction manual under its arm, so there is a need for a natural acclimatisation period. This requires some time investment and farmers should be involved, finding the best way to act”.

All of those present repeated their agreement that M7 is a very interesting orange, not only due to the expectations of possible commercial success that the exclusivity of being a patented variety with limited production (just 2,000 hectares authorised in Spain) could bring, but also because of its high organoleptic quality. “It is a signature orange” one of the farmers claimed, which clearly differentiates it on the market; it is unique because of its firmness, its great flavour and the texture of its pulp.

All of this makes the variety interesting for “brand” traders, who want to have the best oranges for their accredited trade marks, which are then moved on to distribution chains that also want to have the most distinguished and select products. Consequently, these factors encourage “acclimatising” the variety to the conditions of the citrus fruit areas of Spain.

Greg Chislett, Australian breeder of the M7 maintains that the branch cracking, which sometimes results in a partial drying of the affected branches, can be solved with copper-based treatments. On the other hand, Mesejo claims that there has been no link detected in research because there is no evidence of a shortage of that micro element. However, José Antonio, the technician working on a daily basis in the field, notes that appreciable improvements were found with copper oxide treatments. It possible that the reason is that it helped to heal the multiple cracks, which, according to Mesejo, are due to an apparent imbalance between the longitudinal and lateral growth rhythms of the branches due to a climate adaptation issue.

The point is that the problem, which was detected last year, has hardly been apparent this year, whether due to more, less or even no treatment. If it also possible that the problem is disappearing as the trees mature.

The M7 fruit are large in size when positioned well, but they show size deficiencies when bunched together. It is preferable to induce less flowering, or to thin out later, because this variety tends to flower a lot and produces dense blossom. It would be a bigger problem if they didn’t blossom. In this case there are solutions: the controlled application of synthetic auxins to reduce blossom and later encourage excessive fruit to fall, leaving a suitable number for an abundant and quality harvest.

The same strategy of applying auxins works to avoid another problem: the splitting of fruit when it is already fat, something which this year has occurred in all varieties. The use of plastics to reflect light on the floor has also contributed to the improvement.

A general recommendation consists in “giving the variety the greatest strength to overcome the possible deficiencies”. On the other hand, Joan Chavarrías, a Spanish engineer working with Chislett in Australia, notes that there “we don’t force the M7 harvest to degreen, we prefer to collect it nice and ripe so that it can be eaten in its entirety. It is becoming the preferred orange of Asian importers as well because it is very good and it “travels well”.



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