A mild winter's impact on grapes

February 16, 2012

A day of pruning with Bruce Bordelon in the vineyard.

The following is by Bruce Bordelon from the Purdue Wine Grape team. I've spoken to Bruce many times in the past about pruning, spray regimens and dealing with a number of issues in the vineyard. I respect his advice when it comes to growinig grapes in Indiana. Looks like we will be in for a challenging Spring.

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The unusually mild winter has many people asking about what effects the mild temperatures are having on fruit crops. It’s a bit complicated. Most temperate zone plants like apples, grapes, blueberries, etc. go dormant in the fall and will remain dormant even though we may have some mild temperatures during the winter months. They are adapted to this climate by having a “chilling requirement” necessary for them to break dormancy. The must receive a certain amount of “chilling” in order to complete the dormancy process and begin normal grow in the spring. “Chilling” occurs when temperatures are in the range of 34 to 54˚F, with an optimum of about 42˚F. Temperatures colder than 34˚F do not satisfy the chilling requirement and temperatures above 54˚F can actually cause a loss of accumulated hours. There are several models to monitor chilling hour accumulation and the Utah model, developed in peaches, is widely used. The amount of chilling necessary varies by species and varieties, but for most fruit crops is in the range of 500-1,000 hours. Grapes are on the low end of that scale, and vary by variety and species background.

During normal winters, we accumulate some (200 or so) chilling hours in November, but few in December and January, as the average temperature gets too low to satisfy the chilling requirement. Chilling hours accumulate again in February and March, with most crops achieving the necessary hours to fulfill the requirement during the last month of winter. After that point, plants will be ready to respond to warm conditions and begin growth.

This year is unusual in that we received a significant number of chilling hours during December and January. In Tippecanoe County, for instance, we have accumulated 915 hours from Nov. 1 to Feb. 1. During the same period in 2011 we accumulated only 373 hours. At 915 hours we have satisfied the chilling requirement for grapes, raspberries, blackberries and peaches. Apples and blueberries need 1,000-1,200.

In addition to being no longer dormant, plants have also likely experienced cold hardiness de-acclimation in the past month. My colleagues in Ohio recently posted a nice article on this topic in the Ohio Grape-Wine Electronic Newsletter

So what does all this mean to Indiana fruit growers?

It means that your crops are no longer dormant, probably have reduced cold hardiness, and are ready to grow as soon as we get a few days of 50 degree weather. The risk of winter cold damage from temperatures near zero is diminished as we move through February, but the risk of spring freeze damage would be very high if plants begin growth before mid-March or early April. Recall that the frost free date (50% chance of 28˚F) is early May across central Indiana. We have a long way to go….

What can you do?

Growers can avoid frost damage by delaying pruning as long as possible. Unpruned plants are more cold hardy and their buds develop more slowly compared to pruned plants. Grape growers can also use a technique called “long or double pruning.” This method is especially good for varieties that tend to bud out early. The procedure utilizes the apical dominance of buds on a cane. The first buds to begin growing are those on the tip of a cane, while buds closer to the base begin growth later. To perform long pruning, select canes to be used for fruiting spurs during the normal pruning practice and remove the rest of the wood. Instead of cutting the selected canes back to 3-4 node spurs, leave them long, with 10-15 more buds than desired. The extra buds will help delay the development of the desired basal buds, which helps avoid frost injury. After the date of the last probable spring freeze has passed, the canes are shortened to the desired length to properly adjust the bud number for the vine. Growth of the basal buds can be delayed as much as two weeks if weather conditions are favorable. While this procedure requires an extra trip through the vineyard, it can mean the difference between a full crop and little or no crop.

I would be happy to answer questions and respond to comments.

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Bruce Bordelon, Ph.D.
Professor and Extension Specialist, Viticulture and Small Fruit
Purdue University
Department of Horticulture and Landscape Architecture
625 Agriculture Mall Drive
West Lafayette, IN 47907-2010

Phone: 765-494-8212
Cell: 765-427-0209
Fax: 765-494-0391
http://www.hort.purdue.edu/fruitveg/
 

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2011 Spring Honey Harvest

June 06, 2011

6 medium frames capped on both sides will yield about 1.5 gallons of honey.

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Robbed six, beautiful medium frames of spring honey from one of the hives over the weekend. The timing was right and I just cleaned up the extractor on loan to  me from a friend. To my surprise, I got about 1.5 gallons of honey.

The bees were in a great mood. When I opened the hive, I thought I heard them humming in unison, come, take this honey, for it is good and we'll make more.

The honey was an off-white yellow and very clear, and very thick. The whole family had spoons and we filled our gift jars and put the stores away. I can't wait until all the hives are in full production and I hope for a late fall harvest.

Tags: beekeeping

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Red River Gorge Annual Hike and Camp

February 20, 2011

Saturday morning at the cabin before hittin' Sheltowee Trace towards Cloud Splitter.

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On Presidents Day weeked, about 12 of us headed to the gorge for some cold camping. Planned, well in advance, everyone expected to be camping in the snow. But on the weekend of Feb. 19, our cold spell broke and we were given a sunny weekend for some awesome fun and awsome sights.

Some of us, including myself were a little disappointed we weren't able to do it in the snow, but after the time we had, and a few photos later, we're pretty sure we got our first glimpse of Spring. We had a great group of people ready for some trails, some camping and some good forest food.

On Friday, everyone met at the cabin to plan, talk some smack, eat and drink. After a good nights' rest, we packed up Saturday morning and headed for Cloud Splitter.

We're pretty sure if it had snowed, we may not have been able to hike on some of the trails we did, nor camp in the place we chose. Camp was made at about 1-200 feet from the peak of cloud splitter. There, we had the last rays of sun on Saturday and the first rays in the morning on Sunday.

Cloud splitter features a pretty laborius climb and some serious shimmying to get through a narrow crack and out to the over look. But once you're looking out the face of Cloud Splitter over the whole valley, you think it was worth the effort.

Tags: camping , friends , trips

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Using Paper Chromatography to Monitor MLF in Wine

November 30, 2010

This year, I grabbed 300 pounds of Petite Sirah grapes. I've found that these single varietal dry reds use quite a different process than fruit wines. The vineyard will wait to harvest the grape until it reaches the ideal brix for that varietal so to the winemaker the variables are a bit more controlled than that of a typical fruit wine where the variables are all over the place.

One of the things we do in red wine is undergo malolactic fermentation. This is where malic acid is converted to lactic acid... contributing to more rounded flavors and mouth-feel.

We need to know when malolactic fermentation is completed and we do this through the use of paper chromatography. In this video, I demonstrate the test and explain it as best I can. Hope it's helpful.

Tags: how-to , wine

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A story of Petite Sirah, from the truck to the carboy

November 18, 2010

Many have asked about it... others didn't but still got to hear me blather about it. Here's my story from the truck to the carboy. To appreciate it as I do, you must REALLY like red wine... and then appreciate that it's made right here. I just pressed the grapes off the skins today and it's rollin' in the cellar. I already can't wait to do it again next year. But next year, I think we'll shoot for a clean 500 lbs. Hope you enjoy.

Tags: grapes , wine

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