[NAFEX] tree paint for borers

Hélène Dessureault interverbis at videotron.ca
Thu Nov 13 15:44:08 EST 2008

I use interior latex with lime and a little water to get the right consistency for quick application. It works well. Lime is probably more environmentally friendly than joint compound...

Hélène, zone 3-4
north of Ottawa
  ----- Original Message ----- 
  From: John Bunker 
  To: North American Fruit Explorers 
  Sent: Thursday, November 13, 2008 8:20 AM
  Subject: [NAFEX] screening apples

  Rodent and borer control at Fedco:

  In central and southern Maine non-commercial growers must all deal with apple tree borers.  Some areas of Maine(and other apple districts) do not have problems with borers.  If new to planting apples and wondering if you will have a problem, check with anyone growing apples near you, they'll know.  Commercial growers who use a conventional  spray program generally have limited problems with borers.  The Fedco recommendations are based on our experiences on our farm in Palermo over the past 25 years.

  In our orchard we have tried a number of approaches.  Using window screen seemed like a great idea since the screen would double as rodent deterrence and borer control.  For those who do not have a borer problem, using window screen is highly effective.   I recommend, however, removing the screen during the times of year when you do not need it.  That way the tree trunk will have an opportunity to breath and dry out.   Screen removal  can also be an opportunity to be sure the screening is not girdling or growing into the trunk.

  Using window screen as borer control is problematic.  If the screen top edge is not tight to the trunk, the borer beetles will simply scoot down the trunk behind the screen and lay eggs where you will never see them.  The beetles can also lay an egg through the screen if it lays flat against the trunk.  With screen around the trunk it is also very difficult to see if you have borers in the trunk.  But the time you realize you have a problem, it may be too late.

  We tried stapling the "top" of the screen to itself tight around the trunk to prevent borers from getting behind the screen.  We also tried a foam "gasket".  Both of these approaches have their own problems.  You can never really get the screen tight enough, and if you do, then you are likely damaging the trunk.  The gasket works well, but foams and rubber, etc do not mix well with  tree trunk tissue and we found that the trunks were rotting under the gasket.

  Where we are currently:

  In early November we "screen" all of our fruit trees up to 16" diameter.  For the small ones, we generally use those spiral tree guards.  For larger trees we use old window screening, hardware cloth, etc.  With the screening, we wrap it around the trunk and tie it off with a piece of baler twine.  In April, we remove all the screens and guards. We keep our trees "weeded" around the base during the growing season.  We have never experienced any rodent damage during the growing season. 

  All trees are weeded and mulched with chipped brush.  Eventually the brush bits disappear and  more is laid down as available.  The mulch is kept back about 3 inches from the trunk.  This leaves a "moat" of soil around the trunk.  We then paint the trunk up to about knee-high with a mixture of interior white latex paint and "sheetrock" joint compound.  The mixture is like a thick paint, not a paste.  It paints on.  We dig down into the soil a little bit - say 1/2"- and paint right down to the soil.  Then, gently pull the soil back over the paint up against the trunk.  We don't wait until the paint is dry to do that last step.  The paint and joint compound are cheap and easily accessed.  Hardwares stores occasionally have "returned" gallons of paint for $5.  We prefer interior (rather than exterior) paint.  Exterior contains ingredients that might damage trees.

  (This mixture is NOT  organically certifiable.  We also developed a certifiable mixture using linseed oil, milk and quick lime.  This also works, but does not adhere to the trunk very well and therefore requires more frequent re-application.  Although we use organic practices in our orchard, we are not certified.  We vastly prefer paint/joint compound.)

  Using either paint method is an excellent deterrent.  However, the paint does not kill the borers, so they will be around.  Over time, the population may decline, but in high-pressure areas, they may not do so.  It is critical to continue to regularly check all trunks for the "frass" that is the sign of borer activity inside the trunk.  They do occasionally still get into our trees.  The paint must be reapplied every year.  It wears off, etc.  When we do find borer sign, we dig/cut out the borer.  Even serious surgery on the young tree is better that leaving the borer inside.  Having the trunk painted white makes it very easy to spot borer activity.

  Best regards,
  John Bunker
  trees at fedcoseeds.com
  PO Box 520
  Waterville ME 04903
  fax: 207-872-8317


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