Optimism around guava industry, despite disease impact

The South African guava industry is primarily based on a local cultivar called Fan Retief with a vivid salmon pink flesh. The cultivar derives from the original guavas brought to the Cape via Madeira by the early Dutch settlers in the seventeenth century.

As a tropical fruit with no frost tolerance, most of the industry is based in the Western Cape and also in the subtropical north of the country, like Levubu and the Mpumalanga Lowveld, but guava prospects are very different in these two production regions.

The Western Cape has seen a renaissance in guava production, driven by the canning and juicing industries. The vast majority of the guavas produced in the Western Cape are meant for processing, of which about half are exported in the form of purée. The particular pinkness of the guava cultivar Fan Retief is highly prized by international juice producers and is mostly unmatched by guavas grown elsewhere, with the exception of some Brazilian and Indian cultivars.

The guava industry is still a relatively small one in the Western Cape, with about 650ha planted, but there is steady growth. “We’re very optimistic about the guava industry in the Western Cape but we want it to grow slowly with the current growers,” says Poena Malherbe, chairperson of the Guava Producers’ Organisation. The organisation is investigating new cultivation techniques, inspired by the topfruit and stonefruit industries of the Western Cape, like new trellising methods to improve yield and facilitate harvesting. “We’re hoping for another harvest of 25 000t in the Western Cape this year but with the drought we probably won’t reach that.”

The big distinguishing feature of guava production in the Western Cape is the absence of a devastating bacterial soil-borne wilting disease that has wreaked havoc in the guava orchards of Limpopo and Mpumalanga, so much so that it’s estimated that there are but a handful of guava growers left in the Nelspruit area. The entire guava industry is primarily based on the same cultivar, Fan Retief, which could put it in a precarious position if the disease were to spread southwards.

Research into new wilting disease-resistant varieties

The Agricultural Research Institute’s Division for Tropical and Subtropical Crops had come up with a wilting disease resistant cultivar in 2000, the TSG2 cultivar, but since 2009 this has also become vulnerable to the disease. “We think that the disease has mutated,” says Salomie Willemse of the ARC in Nelspruit, who runs the facility’s guava gene bank with material from across the world from which she makes crossings to obtain a new resistant variety. Her guava research also includes gamma radiation (which has resulted in guavas with better colour and fewer seed, which is what they’re aiming for) as well as attempts to germinate guava seeds in a medium containing a toxin of the wilting disease, in order to promote resistance.

Why the disease doesn’t occur in the Cape, is not known for certain, and it is too much of a risk to take the pathogen down there to test resistance. For this reason, guava trees may not be moved from the north to the south of the country.

Guava orchard at the ARC Nelspruit experimental farm (photo supplied by Salomie Willemse)

“We’ve identified a number of promising and potentially disease-resistant selections from our breeding programme in Nelspruit, where we don’t have the disease on our farm, and in February this year we planted young trees of 28 different selections at the Infruitec-Nietvoorbij farm in Simondium in the Western Cape as part of our phase 2 evaluation to increase our plant material under the different climatic conditions of the Cape,” she continues. All of these selections (which will be augmented with another 21 selections) were also chosen on the basis of a pink flesh colour, fewer seeds and larger fruit.

The holy grail would be a pink-fleshed guava with much improved shelf life that could be exported as fresh fruit, or even just be transported across the country, for the Fan Retief guava has such a short shelf life that Western Cape guavas cannot be sent to fresh markets in Gauteng.

Guava production in the north of the country

In the north of the country, production has decreased dramatically due to wilting disease. Kosie Eloff of Agrivet in Soekmekaar, Limpopo Province, who still has 10ha under guavas, explains that the disease kills off entire trees and is so contagious that infected soil has to be re-assigned to different crops. (The other factor reckoned to have dented guava production in the far north is the number of previously productive guava farms since transferred as part of the South African land reform process.)

The impact of this disease on the northern guava production areas can be seen in a drop of approximately 70% in guava volumes on the Johannesburg fresh produce market over the past two years, says Alex Christodolides of Botha & Roodt market agents. “We used to get 20 or 25 pallets a week but now we’re down to about seven pallets a week, that’s around 7 or 8 tonnes a week.” The high prices that fresh guavas receive is a

function not so much of demand, but of limited supply. Be that as it may, guava suppliers are happy at the R18 (€1.13) to R25 (€1.57) per kilogram fresh guavas currently command.

Another Limpopo guava grower that is still going strong, is Amana Boerdery in Levubu, although their current volumes of 200 to 300t is down quite a bit on the 700 to 800t of previous seasons. “Wilting disease is more aggressive than in the past and there are no chemicals against the disease,” says Piet Muller of Amana Boerdery. “The disease reduces the longevity of a guava orchard. Normally a guava orchard can produce for thirty years or more, but now we plan for an orchard to only be productive for 10 or 12 years.”

This farming enterprise, which also grows avocados, macadamias and passionfruit, starts its guava harvest in May, when they have packed most of their avocados, and the guava season runs until September or October. They currently have 12ha under guavas but hope to expand it to 30ha over the next two years, within the constraints of wilting disease and availability of uninfected soil. (They have benefited from the drought over the past three years through replacing disease-stricken guava orchards with papayas, but during normal rainfall seasons Levubu is too humid for papayas.) They send around 40% of their guavas to the fresh produce markets and supermarkets, where the fruit is considered of outstanding quality, and the rest goes for processing.

The soft pink guava, particularly rich in vitamin C which made it a prized item among the Portuguese and Dutch seafarers, is well-loved in South Africa in all its forms (fresh, juiced and dried).

For more information:

Poena Malherbe

Guava Producers’ Association

Tel: +27 21 872 1501

Email: poena@xsinet.co.za

http://www.guavaproducers.co.za/

Salomie Willemse

Agricultural Research Council

Tel: +27 13 753 7000

Email: salomie@arc.agric.za

http://www.arc.agric.za/

Piet Muller