Top Mistakes of New Grape Growers – Our Intentions are Always Good…

Healthy first year vineyard in Texas.

Healthy first year vineyard in Texas.

I have worked with many vineyard startups over the past decade, instructed at numerous prospective winegrower workshops, and evaluated new vineyard sites with the enamored new owners claiming to be bitten by the vineyard bug. Accurately diagnosing vineyard problems for new growers is one of the most rewarding parts of my job. However preventing them from occurring is the ultimate goal. Even the most experienced of growers has the occasional slip through the cracks. In hopes that some new grower will stumble upon this entry, I am hoping to help that individual avoid some of the most common and most costly mistakes I have witnessed first-hand. This list could be quite large, thus I have pared it down to those issues big and small that seem to crop up most frequently.

 

1. Using the same spray tank for herbicides and grapevine spray products

This problem does not need a great deal of explanation. But let’s just say that no matter how well you think you can rinse out the tank and nozzle of your sprayer, you will never rinse it well enough to remove the split fraction of herbicide that will inevitably mangle or even kill your young grapevines. The bigger problem occurs when residue from a systemic herbicide is left in the tank, killing a vine down to the roots.

Advice: If you choose to use herbicides in the vineyard, designate a separate spray tank, clearly mark it as “herbicides only,” draw a picture of a dying plant on the outside, or whatever it takes to avoid this error. Use another tank for all sprays that will end up on the vines.

2. The “double spray” dilemma

Double spraying of boron fertilizer caused foliar toxicity.

Double spraying of boron fertilizer caused foliar toxicity.

New growers often have a tough time “guessing” how much water to mix with their spray product to cover the foliage of all vines in the vineyard. To add to the complexity, the vines just keep on growing (if you avoided mistake #1) which means that the volume of water needed will increase over the course of the season. The “double spray” dilemma occurs when a grower mixes more spray product than they need to get full coverage in the vineyard. Not knowing what to do with the remainder, and not wanting to waste it, they may be tempted to go back in and “use it up” on a few rows of vines that have already been sprayed. This may not cause a problem with some products, however many foliar fertilizers (e.g. boron) and some fungicides (e.g. phosphorous acid) can be toxic to grapes if applied at close intervals. The label rate is designed to prevent leaf burn, but a grower might double that concentration by spraying a second dose within hours of the first.

Advice: Watch for product labels that provide a ratio of water along with the rate per acre, as these are often the products that build up in vine tissue to toxic levels. If in doubt about the amount to mix, try putting a gallon of water in your sprayer and testing how many vines it will cover – this will help you to estimate the total number of gallons you may need for the entire vineyard.

Double spraying of boron fertilizer caused foliar toxicity.

3. Waiting until after the rain to apply fungicides

Downy mildew lesions on the underside of a Lenoir leaf.

Downy mildew lesions on the underside of a Lenoir leaf.

Whether or not you choose to use fungicides (organic or otherwise) there is a common misconception by new growers that the fungicide should not be sprayed until after the rain has passed. After all, why would someone choose to apply a fungicide if it is just going to get washed off by the rain, right? Most fungicide products work is as protectants; applied before conditions are adequate for disease growth in order to prevent or slow the disease spores from growing. There are products intended to be used during the post-infection period (after the rain) and others to be used as “erradicants” to clean up a disease that has taken foot hold on vine tissues. However, by the time you see the disease it has likely been growing for a week or more on the vines at a microscopic level. Some products work systemically to prevent fungal diseases from infecting tissues, while others work just on the surface where they are sprayed. Choosing which product is best for each weather scenario is one of the most challenging concepts to grasp for new growers, and is indeed what I spend much of my time helping with as a consultant. Let’s just say that it is better to have the product down before that long wet period where fungal spores will be plentiful and searching for susceptible vine tissues. Would you wait until you were soaking wet to put on your raincoat?

Advice: Use fungicide products proactively, to prevent disease rather than reactively to attempt to fix a problem. This usually entails spraying before rainfall or other conditions that favor the growth of fungal diseases. Consult with your viticulture advisor frequently during challenging weather!

4. Not removing grow tubes for the winter

Plastic grow tube used to protect young vine from animal feeding and herbicide damage.

Plastic grow tube used to protect young vine from animal feeding and herbicide damage.

Grow tubes are commonly used to protect young vines from several potential problems, such as feeding by rabbits and other critters, damage from high winds, and drift from herbicides used to control weeds in the vine rows. Some growers in cooler climates may also get the added benefit of enhanced early season growth from the greenhouse-like growing environment created by the plastic or cardboard tube. However it is exactly the latter of those effects that can lead to issues in the winter months if the grow tube is not removed in the fall. Grow tubes left on young vines over the winter will cause the air immediately surrounding the young trunk and graft to heat up during a sunny day. The warm daytime temperatures may de-acclimate vines, followed by cold evening temperatures that lead to damage of the trunk tissues.

Advice: Remove those protective tubes in the fall, let the vines go to sleep for the winter, and don’t nudge them until pruning time.

5. The indiscriminate “weed” whacker

Crown gall on trunk of young vine.

Crown gall on trunk of young vine.

The title should say it all on this one. Uncontrolled weeds that grow into the canopy can be a big problem for young vines. Weeds compete so well that even watering and fertilizing young vines is not enough to compensate. It can be tempting (and physically satisfying) to run in to the vineyard with the power of a petrol fueled weeding hand. But is your aim really that good? No matter how careful one tries to be, the end result is always a few scuffed trunks or denuded graft unions. The physical damage in itself may heal fast. The bigger problem is a gall forming bacteria called “crown gall.” These bacteria are often found in a quiescent state in the trunk tissue of vines and are stimulated by injury to the vine trunk or cordon. Crown gall can lead to death of the vine if found below the graft union, and may weaken what could otherwise be a strong vine. Crown gall is most commonly associated with damage from cold winter events, but even in the warm south the occasional human induced injury (known as farmer’s blight) can have the same effect.

Advice: Keep the weed whacker in your lawn, on your fence line, and out of the vineyard.

6. Not reading product labels

This issue tends to come up with the “weekend warrior” grower. A new vineyard is very demanding on time, thus a lot needs to get done on the weekend for these folks. It is indeed possible for a part time grower to have a day job during the week and still manage a productive vineyard. I have witnessed some perfectly manicured one or two acre vineyards managed in this style, but a new grower has a lot of reading to do before they can just jump out of their vehicle on a Friday evening and start working on their vines. The new grower may glance over the label of a pesticide too quickly, leading to problems such as improper measurement, inadequate use of personal protective equipment or mixing of incompatible products in the same spray tank (e.g. sulfur should never be mixed with oils). As an advisor to many growers it is tempting to provide the quick answer for a mixing rate for a product, but I try to encourage new growers to read the label and learn how to find the answers quickly. Things that all new growers should learn to identify on the label of any product used in their vineyard include the pre-harvest interval (“PHI”), re-entry interval (“REI”), maximum rate per acre per application and per year, and required personal protection equipment (“PPE”) for mixing and applying the product.

Advice: Learn how to find the most important safety and regulatory information on product labels. Highlight it and train your crew accordingly. Remember, the label is the law, and knowing what is on it will protect both you and your vines from harm.

Iron toxicity caused by a tank mixture of chelated iron fertilizer and an oil based surfactant.

Iron toxicity caused by a tank mixture of chelated iron fertilizer and an oil based surfactant.

7. Too much of a good thing

We have all run into this example at one point or another. If a little is good, then a little more must be better, no? New growers learn over time that there is a common thread that is discussed in all viticulture circles, a concept known as vine “balance.” Vine balance, in short, is defined as a vine that is growing in equilibrium with its environment, at a steady and productive pace. A balanced vine will have a ratio of fruit to leaf area that falls within a range that allows the fruit to ripen to the quality level desired without overstressing the vine (or overcropping). The concept of balance is subjective in many cases, but also can be measured using a simple index of fruit weight to dormant cane weight, known to viticulturists as the “Ravaz Index.” The most common mistake a new grower can make with young vines is to apply an excessive amount of fertilizer. Application of excess fertilizer not only wastes money, but can also end up polluting ground water or accumulating in soil to cause root burn or leaf burn, and inducing high vigor growth of poor quality wood for trunk and cordon development. Growers should be extra cautious about applying foliar fertilizers too frequently to avoid burning leaf, flower, or fruit tissue.

Advice: Approach vineyard fertility with balance in mind. Use the results of soil and plant analysis as a guide for precision fertilization, adding only what is needed, and when it is needed. Be careful not to spray high concentrations or incompatible mixtures of fertilizers on foliage.


 

If you are new to grape growing, I sincerely hope that the above examples can help you to avoid common mistakes with your new vineyard. If you have been growing grapes for a few years, I would challenge you to find a common mistake that you have not already learned the hard way. I certainly have, and would say that there is no better way to learn than by “doing.” Feel free to leave your comments below if you have another story for new growers to learn from. And please contact me if I can help to diagnose a problem! The chances are high that I have seen it before.

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