Skip to main content

Removal of clusters and canes from the vineyard?

I just saw Tony sent an email this afternoon to discuss about the sanitation issues.  I want to add a few more comments here to discuss this important issue.  (by the way, if you would like to be listed to Tony's email list which he also uses to publish his quarterly publication "Viticulture Note", please let me or Tony know)

Since we finished the season with long rainy periods, some of you experienced increased level of downy mildew and/or Botrytis.  In addition, I have seen several outbreaks of ripe rot (which I will discuss in the next posting), and other general rots (sour rot, Aspergillus, Penicillium, etc.).  Because of that, we probably have a higher risk of having these diseases in the next season.  The question is how to deal with them.

As Tony noted, it is probably a good idea to move them from the vines and place them in the middle of the row, then remove or mow.  If the berries are hanged in the trellis, these can be sources of inoculum in the next season.  Since many of these pathogens are splashed by rain, having a large number of spores right next to new growths is a bad idea.  Also, by mowing the debris, it will help decomposition of these infected tissues.  I have seen berry debris directly under the vines that were covered with Botrytis spores in the spring.  Since there were no green tissues around, I do not know what it meant in terms of disease development for the season, but it just made me realized that they do survive through the winter in these tissues.

The question is what you can expect from these sanitation measures.  Unfortunately, many of grape pathogens can complete their lifecycle in a short period of time (2-4 weeks), thus the effect of sanitation does not last long.  Therefore, even if you do a good job of cleaning up your vineyards, it will not allow you to skip any of early season sprays.  However, it will help reducing the risk of outbreak early in the season.  If the environmental conditions were very favorable and there were abundant spores, you may face the risk of outbreak from the get-go of the season. 

Tony covered about cluster, but how about canes and pruning woods?  The same principal will apply here.  However, the difference is that these woody tissue are more resilient to decomposition, and some of pathogens, such as Phomopsis, Botryosphaeria, and Eutypa can survive in the woods for several seasons.  Since both Phomopsis can Botryosphaeria can produce spores from the infected 1st year cane, if you leave them on the ground, chances are they can be the source of inoculum for the next season.  Spores of both pathogens are splashed by rain (some of Bot species can produce airborne spores, but it seems that rain splashed spores are the majority), thus, the closer the canes to the main trunk, the higher the risk is.  Say, if you have infected canes nearby trunk and the trunk is damaged from winter injury or other means of wounding event, you can easily imagine that these pathogens move into the wound and cause problems later.  Thus, it would be nice to remove pruned canes from the vineyard, or at least chop them down in the middle of the row. 

If you are making a big cuts, make sure to take them out from the vineyard.  You are cutting big pieces probably because of diseases, and leaving these old trunks or cordons in your vineyards won't do any good for you.

Comments

  1. Hi Mizuho. Is there any reason why unharvested clusters should be removed before we prune? If not, I would rather just remove all prunings, including clusters, in one pass. Thanks.

    ReplyDelete
  2. Hi Jeanette,
    It probably does not make much differences whether you do it before or after pruning. The infection to new growth is more important (and probably more likely to happen) than infection to older growth.

    M.

    ReplyDelete

Post a Comment

Please leave your comment here. In order to avoid spam messages, l moderate comments, thus it may take a few hours for your comment to be posted on the page.

Popular posts from this blog

2021 Pest Management Guides for grapes (UPDATED 24 March 2021)

Updated: Links below are for the 2021 edition of Pest Management Guides. The first one is for home gardens, and the second is for commercial productions. I asked them to provide by chapter (= crop) and they made changes. :) 1) Visit the page by clicking one of the links below. (It is rather a slow page. Please be patient.) 2) Scroll down until you see "Links to individual chapters." Grapes are chapter 3 for both Home (Home Fruits) and Commercial Crops (Grapes) 3) Once you get to the site, click "PDF", then "Preview", and it will open a new window.  4) Scroll down a bit, and click "Download Version" to download the file to your computer.  2021 Home Grounds  Pest   Management   Guide 2021 Horticulture and Forest  Pest   Management   Guide

At bloom disease management tips

Recent cooler weather seems to have slowed down vine development, but it looks like vines in the south are about to bloom. Bloom is a start of the critical time for cluster infections by downy mildew, powdery mildew, black rot, Botrytis, and ripe rot, because pathogens of these diseases can infect flower parts and develop symptoms later. What I recommend often is the use of protective materials to protect tissues for 4-6 weeks for V. vinifera varieties, and 3-4 weeks for V. labrusca varieties, which should translate into 3-4 sprays for V. vinifera , and 2-3 sprays for V. labrusca .  If you have hybrids, they are somewhere in between, so, 4-5 weeks to be protected.  As usual, please make sure to rotate mode of action (= FRAC) groups. Since we have not seen many rain events, I think powdery mildew will be the primary target for many of us. But please check your local weather to make sure, some downy mildew susceptible cultivars may still show downy mildew, especially, if there are many

Downy mildew gallery

At Winchester, we had light rain events during the night of 6/12/09, but it was short events and the relative humidity was low (80% or so), thus it probably did not promote any infections. However, we are experiencing continuing favorable nights for downy mildew sporulation (average T>55F, high RH (80-100%)) for 10 days now. Yesterday, we conducted a formal disease assessment, and observed first incidence of powdery mildew for this season. We had plenty of infection events in last two months, so it was not surprising. At this point, it is a trace level of infection on untreated vines. Downy mildew was the major disease so far. We had up to 40% incidence on untreated vines. Next runner-up was black rot. It varies vine to vine, but some of vine had 10-15% incidence. Phomopsis was omnipresent as I expected from early May rain falls, but severity was low overall. We will examine diseases again in the near future, and I will update as the season goes. Here is downy mildew ga