What are stem borers or bhriud?
The larvae of stem borers are commonly known as squash vine borers, as they burrow into the zucchini vine and other vegetables like pumpkins, i.e. one belongs to the cucurbits family (cucumbers and melons are not usually a problem). Once the vine is infested, the larvae feed for about four weeks, destroys the plant tissue and causes it to die. The plants die because larvae thrive within the lower part of the stems.
Stem Borers can be controlled only by preventing the adult moth from laying eggs on the plants or killing the larvae before they infect the vine. Once the larvae burrow into the vine, it is challenging to avert the damage. Controlling Stem Borer or Bhirud is mainly about prevention.
The adult clearwing moths emerge from early to midsummer and lay eggs singly or in tiny groups at the stem base. The eggs hatch within one-two weeks. The larvae then get into the stems to feed for about 2 to 4 weeks; at times they attack the fruit too.
How to identify stem borer or bhirud?
- Eggs: Stem Borer or Bhirud lay tiny, flat, oval, and brown eggs. The eggs are laid scattered mostly at the base of squash and pumpkin plants.
- Larvae: To find the larvae slit open a stem lengthwise with a fine, sharp knife. You would notice a fat, white, wrinkled body and brown head insect that can be about an inch long.
- Moth: The adult and fully grown stem borer or bhirud look like a moth, i.e. about ½ inch long and looks a bit like a wasp with a black body, and flanked with orange-red stripes. Its hind wings are transparent, and the front wings are metallic green.
Damage caused by stem borer or bhirud:
- Plant leaves will appear to wilt.
- The base of the plant will show holes and green to orange-yellow sawdust-like frass or droppings.
- The stem will rot from the areas where the stem borers feed.
Control & Prevention of stem borer or bhirud:
- Lookout for signs of stem borer infestation and if you catch it early, you can pick and remove Stem Borers.
- Slit open the lower stem lengthwise with a sharp knife and remove the larva by hand. Once disinfected, cover the slit stem section with moist soil to promote the formation of secondary roots. Also, add rich soil near the slit vines for rerooting. Remember that one plant can house several.
- If entrance holes and “sawdust” appears, kill the inside larvae by inserting a wire and thread through the stem up to some distance.
- When Stem Borers are small, and in their nascent stages you can use Torpid, Tafgor or Pyriban. These can be purchased at Ugaoo.com
- You can sprinkle black pepper around the plants as the part of defence mechanism.
- The moth rests on the upper surface of leaf bases at twilight or in the early morning. Thus destroy these moths at that time.
- Use insecticides to get rid of Stem Borers, but the timing is extremely crucial. For effective results, you need to apply them when eggs are hatching.
- The adult moths can be trapped with yellow sticky traps and yellow-coloured soapy water bowls.
- An age-old folk remedy states that wood ashes are very effective against the stem borers.
Prevention of stem borer or bhirud?
- In case of Stem Borers, prevention is better than cure.
- Avoid planting squash in the same bed for two consecutive years. Keep in mind that squash vine borers overwinter in cocoons under the ground.
- Before planting clean up your soil.
- Once the squash is harvested, discard the vines. Till the soil to get rid of overwintering pupae.
- Stem Borers love Blue Hubbard Squash. Thus you can plant it around zucchini and other squashes to prevent the moths from attacking the main vegetables.
- Cover the stems strips of nylon stockings or aluminum foil, as they act as a barrier and prevent egg laying. Anchor the covers so that the pests cannot get underneath them. This only works if no moths are emerging from burrows under the covers.
- Introduce parasitic wasps before the eggs are laid, as wasps are borers’ natural enemy.
- You can cover crops with floating row covers to prevent egg laying, drape these row covers over frames. This will protect your plants from temperature extremities.
- Grow snake gourd as it is more resistant to Stem Borers.
- The squash bug is a squash and zucchini predator.
- Crop rotation is the key to get rid of stem borers. Avoid planting cucurbits in the same plot, or plant cucumbers, melons or watermelons as borers hardly threaten them.
- Lastly, you can cut off the infected vine and cover it with additional soil for new root growth.
Do you have any organic tips for controlling these pests? Let us know in the comments section below!