6.08.2013

Squash Vine Borer

Last year we were saddened when several of our plants were attacked by the squash vine borer.  I discovered the pest after running inside to my computer to find out why our zucchini plant had looked perfect the day before and completely wilted the next!  


Sad wilted Zucchini plant
The pest: Squash Vine Borer

The problem: Last year it attacked our (3) Summer Squash and (2) Zucchini plants! 

Squash Vine Borer- Ohio State University Fact Sheet


Adult Moth (Squash Vine Borer)


I quickly discovered that the red and black bugs that were swarming around me sometime around June were the beginning of the end for my plants (If only I had known then the damage they would do!) 
Dull red colored Eggs  of the Squash Vine Borer

It was now July and when I split open the bottom of the stem of my wilted plant sure enough I found a white larva munching away.  The truth was that these moths had laid their eggs on my plants back in June and they had turned into larva that climbed into the stem and had been eating away at the plants for more than a month!  It was a very disappointing day indeed because we realized our other zucchini plant and 3 other summer squash were just days away from the same sad end.


Larva (Squash Vine Borer) eating the inside of stem
Hopefully I can save you some loss in your garden with some of this preventative information!



The life cycle:  Egg, Larva, Earthen Cell, Pupa, Adult (male or female)

From what I have read the larvae feed on the plant for 1 month and then when fully mature they come out of the stem and make a cocoon in the soil.  Then they stay in the soil over winter and become a pupa the next spring.  The pupa then turns into the adult moth which lays eggs on the new plants turning into larva then the pupa and the cycle continues the next year.  (Usually there is only 1 generation per year in Ohio.  A partial second generation is possible but has not been documented).


b. Moth (or adult) c.part of squash stem cut open to show larva feeding within d.pupal cell in soil cut open to show pupa inside e.typical wilting of squash plant caused by borer feeding inside stem
 To be safe: We got rid of all of the infected plants last year as soon as we discovered the larva in the stems. (A very important step to make).  Hopefully that means we took care of the problem, but I can't be certain.  As you read above its possible that the larvae could have made cocoons in the soil and become pupa (in which case things could get interesting)....the next couple of weeks the truth will be revealed.  In Ohio the pupae turn into adult moths when vine crops start growing which is usually towards the end of June.


Squash Vine Borer damage
 The (possible) solution(s): Around the end of July or mid August I will be able to let you know if any of these possible solutions worked in our garden.  I decided to combine all of the methods listed below to attempt to stop the attacks.  This may seem a little overboard, but from the information I have read it seems that you have the most success if you employee back-up measures and just plan on the borer attacking again.  Especially if you have had damage in the past (we have) which places your garden at a higher risk for another attack!  

Preventative measures are the best (stopping the adult moth BEFORE it lays eggs)
  1. Use Aluminum Foil- Lay it underneath the stem of the plant at the base. This causes the moth to become disoriented. 
  2. Cover Vine with Soil: (works only for vining plants) Cover the vine with soil at several points along the length.  This will allow the plant to root at many points allowing it to continue to feed the developing fruit even if the original stem becomes damaged by the borer.  Then if you find damage (after it has roots at multiple points) any infected portion can be cut off along with another inch where larvae is eating the healthy tissue.  This will minimize damage to the plant.
  3. Check plants at twilight or early morning. The squash moth is active for 2 months (peaking in July) during the daytime and rests on leaves in the evening.  Never EVER allow any larvae to reach the ground.  Catch them and destroy them.  
  4. Wooden board- place the board near your plants and the adult moth borers should all gather in this location.  Then you can destroy them.
  5. Use Row Covers on your garden (especially if you have neighbors that are also growing plants that are susceptible to the squash vine borer).
  6. Wipe stems of plants every 5 days vigorously with a damp cloth.  This should wipe away any eggs which are known to hatch in 7 to 10 days.  (An Auburn University researcher found this in an 1890's book on farming). 
  7. Using a flashlight (at night or early morning) shine the light on the stems and look for any dark forms (larvae).  If you see anything use a stiff wire or needle and carefully push it through to kill the borer without causing too much damage to the plant.
Employ Back-up Measures (if you have had this pest in the past OR if you want to play it safe)
  1. Make succession plantings- (For example if you are planting Zucchini)- plant 1 or 2 seeds every 14 to 21 days so that you will be assured to have fruit during the summer. (If you don't have enough room in your garden for a new planting you can always start it in a container and then transplant it into your garden).
  2. Harvest fruit often (just in case the stem is attacked)
  3. Make sure to inspect each plant everyday and check for signs of frass or small holes at the base of the stem.  If you see either of these then pull the entire plant out of the ground. Put the bottom portion of the stem in soapy water to kill the larvae then dispose of it in the trash.
  4. Plant companion plants- Beebalm, Catnip, Marigolds, Nasturtiums, Mints, Radishes and Tansy.  
  5. Natural enemy is the Parasitic Wasp during the egg stage.
NOTE: If you employ these above measures and have had the squash vine borer in the past as time goes by your problems should disappear. 
  
MORE PREVENTATIVE MEASURES (we will try these next year):

FIRST: Remove all vines completely from garden and compost.  This will prevent any borers in the larval stage from completing their development.  Note: Sanitation for your entire garden is very important after your harvest is complete. 
 
SECOND: Use a hoe to dig in the soil in the area that the borer attacked the previous year.  Search for cocoons about an inch deep and remove any that you find. 

THIRD: Using row cover material cut up little pieces and wrap the stem of baby seedlings before you plant them in the garden.  Make sure to extend the material as low as possible on the stem.  Plant the seedlings and make certain the covered area of the stem extends below the soil line. Continue to wrap the vine with more material as the vine grows. 

FOURTH: Inter plant buckwheat to supply food for a fly parasite (tachnid fly) of the squash bug.  

FIFTH: Plant a trap crop very early of Hubbard Squash.  Then any SVB will attack this plant and leave your other plants alone. 

If all of the above methods do not work (or you just don't want to deal with all this) then you can plant resistant cultivars.  These are vining summer squash that offer an apparent resistant to and tolerance of borer attacks.
  1. Tatume or Tatuma (also listed as round zucchini or Mexican zucchini).  It tastes similar to zucchini and is an heirloom or open pollinated variety.  Gardeners have been growing varieties of C. pepo for the past 8,000 to 10,000 years.   It can be harvested as either a summer or winter squash.   It is harvested when it is the size of a baseball.  This plant can send out vines 10' to 12' in length so make sure you have room in your garden.  (Next year I want to try starting this from seed and growing this vertically!) www.heirloomsolutions.com
Tatume fruit


 







     2. Trombichino (Zucchetta Rampicante, Climbing Zucchini, Climbing Crookneck or Serpentine Squash) This summer squash is an heirloom from Liguria and is a butternut relative.  Like the Tatume it can be harvested as either a summer or winter squash.  The flavor can be compared to a watery butternut squash.  You pick this squash when it is one foot in length. www.territorialseed.com 


Trombichino fruit












3. Waltham Butternut- this is a type of winter squash and the flavor has a nutty taste similar to a pumpkin.  It grows on a vine and turns deep orange when it is ripe.   We grew these last year and this was the only squash that was NOT attacked by the squash vine borer. 


Waltham Butternut fruit














You can also try a Cucurbita moschatta cultivar.  This species shows a higher resistance to disease and insects (including the squash vine borer).  Types are: 
  1. Tromboncino- summer squash
  2. Calabaza
  3. Butternut Squash
  4. Long of Naples squash
  5. Giromon
  6. Dickinson field pumpkin
  7. Kentucky field pumpkin
  8. Long Island cheese pumpkin 
  9. Seminole pumpkin
  10. Neck pumpkin (idea for pumpkin pie)

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