Looks like they start at the new leaves. ground -- especially if they are in a dedicated plant bed -- is to smother For longer-lasting. Use your spade to dig around the hole that used to house the canna bulb in a circle that is 1 foot or so in diameter. Be sure to choose a product that targets lily pads and follow the application instructions carefully to avoid harming other aquatic plants and wildlife. They smell through their feet, and by dispersing these powerful scents, black widows will stay away. But this type of acidity is beneficial for killing weeds. Canna lilies are delightful flowers, and few species of flower can rival the burst of color they lend to summer gardens. As tropical plants, cannas prefer humid air but can tolerate relative dryness, especially if they are properly watered. These are also tiny but are more easily recognized by finding their webs. This larvae survives winter in rolled leaves on the plant. She is a former Clemson University Extension Agent. And the important thing is how much vinegar you apply to the plants root; it will not show any effects or problems. All youll need is a pair of gloves and a trusty spade. Yes! Hand-pick surface-feeding caterpillars and drown them in soapy water. In essence, you are trying to starve the remaining Dilute 2 ounces of neem oil in one gallon of water. Here are some alternative methods you can try: If youre not in a hurry to see results, mulching could be the perfect option for you. How to Get Rid of Canna | eHow Adding the salt to the vinegar does a better job of preventing weed regrowth than vinegar alone, but vinegar is not a permanent solution to all weed regrowth. Youll need to remove any dead or dying leaves throughout the growing season to limit the risk of infection. A white cottony fungus will begin growing on the rhizomes in advanced cases. Thripsare one of these. What Is the Natural Way to Kill Canna Bulbs Already in the - SFGATE Poor air circulation helps it to thrive. Set the lilies back into the ground as soon as the soil is soft enough to work. Make sure the rhizomes are fully dry before tossing them into the compost They are practically microscopic and need special methods to view them and determine their existence.