At the University of Arkansas, Dr. Elena Garcia is conducting research on growing table grapes in high tunnels. I have seen her present results at two conferences, the last being at the Arkansas/Oklahoma Horticulture Industries Show in January. I find the preliminary results interesting, since table grapes are extremely challenging to grow in the south, even with full spray programs.
Dr. Garcia is using a mix of season modification technologies, insect exclusion techniques, and regionally developed fruit varieties in her work. Netting is used on the roll-up sides of the high tunnels to keep insects out, and the plastic keeps rainfall from wetting the fruit and plant, reducing fungal problems.
Her research is showing that Arkansas developed table grape varieties (Faith, Hope and Mars) can do very well under high tunnels. In the field, table grapes start commercial yielding in year three, but in the high tunnel, commercial yields start the year after planting. From an economic standpoint, this is very important.
Yields and fruit quality are higher in the high tunnels compared to field-grown table grapes. Some sprays are still used in the high tunnels, but current research is showing a reduction in sprays. In 2013, only three fungicide sprays were needed in the high tunnel, vs. eight or more in the field. Only two insecticide sprays were used in the high tunnel, vs. four to six in the field, depending on the season.
Dr. Garcia thinks that with more research, she may be able to grow table grapes organically in Arkansas! She is also positioning this research as beneficial for market growers or CSAs who can charge retail prices for their product.
There is established precedent for using high tunnel technology in this way. Dr. Ayanava Majumdar at Auburn University has been working on netted high tunnels for pest exclusion in vegetable crops in Alabama. Some growers in the south have used plastic covered high tunnels during the summer to keep tomato leaves dry, reducing the amount of early and late blight.
At the Arkansas/Oklahoma Horticulture Industries show, Dr. John Clark, a fruit crop breeder at the University of Arkansas, stood up and interrupted Dr. Garcia’s presentation to comment on the work. Dr. Clark said he never expected to see such good quality Arkansas grown table grapes from his breeding work.
I was surprised. You need to understand, fruit crop breeders are not individuals who get excited easily. They spend years working on fruit breeding lines, evaluating their potential before one gets released. Then, over several years, commercial growers evaluate through field plantings the potential for a new variety in the market.
Needless to say, fruit crop breeders learn early to have patience. It can take five to ten years before a variety goes from breeding to acceptance in the commercial market – and that is with small fruits. Tree fruits can take longer.
Dr. Clark said that what he saw in the high tunnels was as good a quality as field-grown grapes in California, which has the best table grape production climate in the United States. However, he did caution everyone that the economics needed to be evaluated.
Combining the technologies of high tunnels and netting opens up the possibility for reduced spray/organic grape production, at least on a small scale. The reader is cautioned that more research needs to be conducted, so if you want to try this, do it on a small scale and don’t invest too much money.
Some issues which need to be addressed include the economics of the system, the potential for disease and insect problems over the long term, and changes in soil conditions, such a pH and salt buildup. Most high tunnel production systems use annual crops, so leaving one crop in place for a decade or more may lead to unforeseen problems.
The preliminary results are exciting for small scale producers and point to ways that season extension/season modification can lead to more productive crops with a little imagination and the application of new techniques. I feel the flexibility of season extension technologies, along with the ease with which growers can experiment with them, is one reason growers continue to exhibit such a strong interest in expanding their use. Dr. Garcia is currently working on a SSARE grant to try to answer some of the above issues.