Monday, August 4, 2014

How to Overcome the Evil Squash Vine Borer

I love the veggies in the summer garden from the cucurbit family: zucchini, squash, and cucumbers. But every spring when the first leaves of the seeds push up from the ground, I know the race is on. Can I get a good harvest from my garden before the Evil Squash Vine Borers destroy my entire crop of plants? It takes a lot of diligence to hold them off, but it IS possible. 

To overcome the enemy, you have to study them. They are most attracted primarily to summer squash and zucchini and occasionally to cucumbers, winter squash, and pumpkins. In my garden, they love them ALL!
They begin as these orange and black flying insects...they just look evil. 

You can try to stop them from laying their eggs on the plants by using row covers of mesh fabric. The only problem with this method is that the row covers also keep away the bees that are necessary for pollination for fruit production. I've never tried this method.

Once the flying insects lay their eggs at the base of the plant, the larvae hatch and bore into the stem of the plant. There is little evidence that they have taken up residence in your plants, but there is some. The first sign is an orange sawdust-like substance at the base of the plant where the borer entered. 

As the borer eats it way along the stem the leaves wilt. This is the time to catch them! If the borer goes unnoticed, it will eat its way all the way up (or down) the stem until it cuts off nutrients to the plant, and overnight the plant goes from a leafy green growth to a limp, flattened mess. Once this happens it is usually too late. 

Once you see the evidence of where the borer entered, take a knife and make a slice vertically along the stem until you find the nasty culprit, a white grub-like larvae.

I know it is hard to cut open the stem of your plant, but it will pay off in the end. If you catch the evil little grub then the plant has a chance of surviving even the worst damage. Cucurbits can regrow roots from any part of their stem, so simply bury the stem past the part where the damage was done and give it a good watering. The plant should be able to recover.

Once you have killed one, don't get too smug! They will be back, and back again, and yet again... They are persistent, so you have to be persistent too! Once they have bored to their hearts content, they dig down into the dirt, form a cocoon and wait to emerge as flying insects in the spring, so it is important not to let them get away.

Here are a few other tips to help keep them under control:
- Rotate plants so that you do not have cucurbits growing in the same area more than once every three years
- Immediately pull up and throw away (not compost) any plants that have been taken over by the insects
- Do not compost any cucurbits that may have been affected
- Plant multiple crops throughout the season so that in case one crop doesn't make it, you have a backup
- Use row covers during early plant development before they are flowering
- Thoroughly till the dirt after pulling up plants so that you expose the cocoons (you may even find some so you can squish them!)
- As plants grow, mound dirt around the exposed stem of squash and zucchini plants to keep them from being exposed
- Keep an eye on you plants, looking along the stem each day to find the early signs of orange sawdust and wilting leaves
- I know it hurts, but keep cutting along the affected stems until you find the perpetrators and then rebury the stems to promote new root growth

Good luck, and good harvest! Do you have any other tips or tricks that have worked?