Vine Health, Maturation and Bud Survival

Wednesday, August 2, 2023


There are a lot of things happening in the vineyards and lots of questions on vine balance or should I keep crop on the vine to slow vegetative growth, what shoot thinning should I be doing, sucker training, and weed control. A lot to cover!


Vine Balance and more


Many are commenting on some signs of highly vigorous shoot growth and the question of trying to reduce vigour and/or the use of hedging this year.  Excessive shoot growth often leads to the formation of bull wood which has less winter hardiness and poor maturation for the winter ahead.  This is to reinforce the no fertilization suggestion I have been making all year and discussed in an earlier blog.


Should I be leaving fruit on shoots to help slow them down? 


The quick answer is yes but only until veraison. Then drop the crop. If there is no intention of harvesting this year, the fruit left behind becomes a prime source for botrytis infection that can not only rot and lead to other problems such as fruit flies and sour rot and becomes a source of pests for any fruit in nearby blocks that you intend to harvest.  It may cost to do this but losing nearby crops intended to be picked is a double whammy.

Fruit clusters on Marquette.

Fruit clusters on L'Acadie Blanc.

What about hedging and deleafing?


If the shoots are growing upwards and then flopping over, go ahead and hedge. In all cases whether there is crop present or no crop to be harvested. Lateral shoots will develop that will help the plant manufacture carbohydrates for the trunk and roots and winter storage and if fruit is present will help fill the crop. The big rule of thumb is no hedging any closer than 30 days to anticipated harvest (if crop is present) and no closer than 45 days from when normal fist frost occurs!  For early ripening grapes this is no later than mid-August and for everything else absolutely no later first week of September. If you are unsure and think you might need it, do it! Do not worry about the tops of vines looking shaggy going into winter – those “carrot tops” are incredibly efficient at capturing sunlight and helping ripen fruit to be harvested and adding much needed energy to winter reserves.

Shoots of Baco Noir growing upwards and starting to bend over.

For cultivars to be harvested, leaf removal will help expose fruit to sunlight for ripening, reduce disease pressure and will make harvesting much easier as I suspect some blocks will be hand picked that might have been machine harvested in prior years. I am a bit wary of machine harvesting in reduced crop vineyards where growth is not strong AND where suckers are being brought up for retraining.  Some harvester lower catch paddles can damage these softer suckers you have spent all year training. This is an individual grower choice and the skill of the harvester operator.  Sometimes with light crops harvesters are operated too quickly down throws in an effort to reduce time spent in the vineyards. Weakened vines and young sucker growth are sometimes injured as a result. 


What about suckers I am training up?


Now that August is here, it is appropriate to think about getting suckers mature for winter survival.  One approach that has been really helpful has been to remove leaves close to the ground on suckers. If the suckers have reached 18 inch or so of growth remove all the leaves near the ground up about 10 to 12 inches.  Removing these leaves does a couple of things. It helps you easily identify the suckers for working around the plant and tying them together so they grow tighter to the old trunks will give you a straighter and strong trunk for use in the future. Secondly removing those leaves avoids messy disease problems and inoculum source later in the season. Thirdly exposure to sunlight will help these soft shoots lignify earlier in the fall and harden off and acclimate better going into the winter. This will make for better choices in spring 2024 for choosing retrained trunks!

Riesling with a lot of sucker growth.

Should I do some shoot removal?


Where the head of the vine is clumped with many shoots and crowding is obvious, yes go ahead and remove the extra shoots to open the head up. Crowded heads make disease control far harder and may impact on maturation of the shots/canes you are looking to keep for 2024. Opening up the head leads to better shoot and vine maturation for the fall and winter and also makes pruning easier in 2024.  A little extra effort now will pay dividends in the future.

L'Acadie Blanc with crowded head growth.

Weed control – 2023 not a fun year for weed control!


This has been the bane of many growers this year. Weed control immediately around the vine, especially younger vines is always a good thing. With suckers present, removing weeds helps fungicide coverage as even a green cane (until it lignifies) can be infected by downy and powdery mildew. Most weeds change the microclimate around the vine to high humidity and slow drying conditions which are ideal for downy and powdery mildew which when infecting the wood can lead to reduce cane hardiness and bud survival.

Weeds growing around grapevines.

So, you can see all of the above are about vine health, maturation, and bud survival to some degree.  If you have questions, send them along to  and we will work to get them answered!