KDL Needs to Be Studied Scientifically

What a growing season it has been.   It began the first week in March with several days at and soon above 80 F.  Many weeks before they should, our buds were swelling and soon after shoots appeared.  At that time, if someone offered me $500 for my eight acres of grapes, I would have taken it.  It did not seem likely that my crop would still be intact two months later, mid-May, when we traditionally feel free of the likelihood of spring frost.

Nevertheless, while there may well have been damage I still have a crop and most growers I have spoken to say they have a crop as well. Some are living on less fruitful secondary buds and so the northland is likely to have a dramatically reduced crop.  Others of us appear to have gotten through the events of spring with little bud damage. With reports of a 5% apple crop in Michigan and a 10% cherry crop in Wisconsin’s Door County, it is amazing we have anything.  Miracles do happen and it would seem many of us have experienced one this spring.

Perhaps the most interesting phenomenon seen in this recent spring has been the occurrence of cold injury to apparently fully hardy vines despite the fact that we never saw extreme cold. Some vines that hardened off normally in fall and appeared to be healthy at that time failed to bud out. Many died back to the ground. For the most part these vines sent up strong shoots when spring came.

The best theory why this may have happened seems to be that the early warmth in March caused the vines to lose hardiness. When it became cold again, not just the buds but the wood itself was damaged and the vine died back. Marquette seems to have been one of the most badly damaged this spring, evidently not from extreme cold but from extreme warmth.

These vines and any cold injured vines can all be treated more or less the same. Keep all the strong shoots that emerge from the root and tie them up so they grow toward the high wires. Next spring select a strong cane to become your replacement trunk and remove the others. You may want to wait until they begin to push buds to be sure which are still alive and which are not.

Although it is tempting to do so, do not select the largest and the most vigorous new shoot. This is usually ‘bull wood”, smooth, light colored, few buds and as thick as your thumb. Such wood appears to be super-healthy but is often seen not to come through the winter as well as somewhat smaller wood. Once you select a healthy, moderate-sized new trunk, train it as you would a new vine. It will have a strong root that needs sustenance and will soon be fully ‘re-developed” and ready to begin bearing fruit again.

One fellow in the foliar fertilizer industry commented that I was really going out on a limb with my support of the possible value of KDL, a Potassium foliar fertilizer. Initially, I did not realize the academic community felt that ‘cryoprotectants” (freeze protectors) are essentially synonymous with ‘Snake Oil.”  Even so,  I did not feel out on a limb.  In fact, when growers report and supply me with photographic evidence of their successful use of KDL in previous frost events, complete with adjacent untreated blocks that were demolished in the frost, I felt it would have been irresponsible of me not to have brought these experiences to growers’ attention.

Please see related story:  Frost Damage Protection for the Small Grower

Something is going on here! If a researcher cannot replicate what has been seen in the field, from a growers point of view, this is close to irrelevant. We are seeing a phenomenon. It could prove to be basically flawed or it may prove to be of enormous value to growers of many kinds of fruits. An open-minded researcher is needed, willing to weather the ridicule of colleagues, willing to undertake a serious study: Speak with manufacturers of these products and see what their theories are as to why their procedures work and collect their experiences. Further they need to interview growers who report it has worked and find out what they used, in what concentrations and when. Study their photos and stories to become comfortable with the fact that the phenomenon is real. Is it not a scientific procedure to see what is going on and study it? Coming into a study simply to disprove it is clearly not true science. Someone has a great opportunity to prove to growers how to use a powerful tool.  I hope some strong researcher can step up and make the commitment.

This story was reprinted with permission of the Minnesota Grape Growers Association (MGGA) and first appeared in MGGA’s “Notes from the North.”  Midwest Wine Press is proud to be a member of the MGGA.   Please visit their website at mngrapegrowers.com

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