Fall in the Subtropical Vineyard
Updated: Mar 3
November 2021 - Table Grapes for Hawai'i Research and Education Project
Welcome back to our second Grape Blog. It's now November 2021 and much has happened over the past 3 months so we would like to catch you up on Gerry’s grape and vineyard observations.
The summer 2021 grape harvest was thin all around, in quantity and taste due to the very unusual cold wet weather over the past two years on the Kona Coast. Usually Kona experiences a wet/dry seasonal shift, with wet spring/summers and dry fall/winter. Grapes will not do well in high rainfall areas with no dry season.
Also, Gerry changed his pruning techniques last winter and modified the Geneva Double Curtain pruning system that he had been using. This method of training grapes was developed at Cornell in the 1960s and is a way of using the trellis system with 2 wires horizontally to double the amount of sunlight that reaches the leaves.
Before the Winter of 2020-2021 Gerry was pruning back approximately 75% of each vine in late February. What he observed was that grapes grow incredibly fast in in the subtropics some varieties growing up to 35 feet in a single season in each direction overwhelming the vineyard. The wild parent in the line was showing itself in this subtropical environment. Time for Plan B.
Plan B was to increase the amount being pruned. In the winter of 2019 90% was pruned, but there was still too much growth. So in the winter of 2020, he pruned 98% of each variety and there was still a lot of growth but manageable growth. Gerry continues to observe, ponder and log in his observations in the process of discovering the differences in the amount of pruning per variety. Remember we have vetted 50+ varieties over the past 6 years and we have 16 varieties remaining that are from 1-6 years old.
There are many pruning strategies in a vineyard. Because we have so many varieties of table grapes that we are trialing, it became obvious that some grapes grew better with one type of pruning over another. Here are the four types of pruning that Gerry has incorporated into the Trial, you could call this a “modified” Geneva Double Curtain. Gerry is looking for each variety to express itself in these four different ways. (The “modified” Geneva Curtain)
Gerry has observed that some grapes produce best with “long arm pruning.” Since grapes clusters usually grow on last years wood (but not always in the subtropics) leaving approximately 8 feet of old wood seems to work well. Gerry has added additional wires perpendicular to the 2 outside wires to concentrate the space for the older wood.
Some varieties produce better when the older wood is closer to the main trunk. Mid-arm pruning leaves approximately 4-6 feet of old wood.
Some varieties seem to produce best closer to the main trunk. These varieties are pruned to 2-3 feet from the main trunk.
Spur pruning is a technique that is used to increase production in wine grapes. In this technique you use the same section of old wood, and prune back this years canes (spurs) growing out of that old wood to 2 buds. (see photo)
Because we are working with so many varieties each with their own demands, Gerry will use all these four pruning techniques depending on what the grape is telling him from the past year’s growth.
In February 2022, when he prunes the 5 vineyards, we will be taking photos and creating videos of the pruning techniques so that you can see each of these techniques.
Grape Observations & Weather Fall 2021
At the end of September, the two years of incessant rain just stopped. Since then, it has been sunny and dry everyday, the change has been dramatic. The National Weather Service has not been able to describe what happened over those past 2 years, but we could call this a climate change “event.”
The fall days we are experiencing now, are warmer and drier than summer, the nights are cooler, and the grape leaves are starting to dry up and fall off as the vines go into dormancy, but we still don’t know the effects on next year’s production. The Chinese Beetles who didn't’ like all that rain, are now emerging to help the vines into the winter dormancy. Gerry uses the Chinese Beetle as an indicator of whether or not that variety will survive long term. When the beetle eats all the leaves from the older to the newer leaves, those varieties get “red flagged” meaning that in the next year if this continues to happen the variety comes out of the vineyard. We have not seen any of this before but we know it is a combination of pruning, weather, and varietal differences. There is so much to learn about grapes for the subtropics.
During Gerry’s research over these past 3 months, he was reading Dolmas recipes (stuffed grape leaves see Blog #1) In one of the recipes the author suggested NOT using wild grape leaves because of the “felting” fine white hairs on the underside of the leaf. What he discovered is that many of the grape varieties we are trialing have “some” wild parent genetics in them, and so, have felting on the underside of the leaf. The good news is that this felting protects the leaf from being eaten by the Chinese Beetle! These grape varieties that are crossed with wild parent genetics are proving to more adaptable to the subtropical environment.
New Grape Resources
We recently added two new documents to our Grape Resource Page on the website. This includes links to some of Gerry’s most influential research books and articles, and we will continue to add more information this year and next. Please browse and download or read online at your convenience. https://www.kawanuifarm.org/copy-of-grape-resources-1
I recently made two NEW short Grape Videos with Gerry in the vineyards and have posted them on the Video page. This month, the conversations with Gerry are about what he is seeing in the Fall vineyards and a discussion of one of our organic practices.
Posting Photos on Instagram - #grapesforhawaii
Thanks so much to those of you who posted some of your own grape photos on our Instagram page #grapesforhawaii. Over the past 3 months, a few of you have told us stories about the grape you have in your garden or on your farm, so if you have time, please post a photo or photos showing what your grapes look like in the fall on Instagram #grapesforhawaii Then we can all see what is growing in Hawaii’s grape world!
New Photos on our Website
We have added new fall photos of the grapes on our photos page. Please check them out!
Two housekeeping items.
Yearly Grape Workshop at Kawanui Farm: Because of the ongoing pandemic, instead of doing an in-person workshop here at Kawanui Farm in 2021 or 2022, we will be creating 10 short videos about grape production and posting them on our website each year.
Making Comments on our Blogs: We have created a simple way for you all to comment on our Grape Blogs, and get a conversation going. When wanting to comment on a blog open the blog and the comment box is on the bottom of the page. You can also reply to others comments.
Mahalo to all of you for coming along with us on our 2 year grape journey to find subtropical table grapes that will thrive in Hawai’i. Mahalo to our Mentor Ken Love and to all the folks at Western SARE (Sustainable Agriculture Research & Education & NIFA programs at the USDA) for their continued guidance and support for farmers across the West.
In our next Blog, February 2022, we will be sharing videos showing our Winter Vineyard Pruning techniques, and making and starting scions of grape varieties. Until then, we will continue to post new photos, 2 new videos each month, and new Instagram photos and descriptions.
Gerry Herbert and Nancy Redfeather
"Table Grapes for Subtropical Hawai’i" is a project made possible by SARE: Western Sustainable Agriculture Research and Education Initiative at https://western.sare.org 406-994-4785, and NIFA,https://nifa.usda.gov/
If you are interested in purchasing Ken Love's beautiful Grape Poster go to https://www.htfg.org/product-page/grapes-poster