Root Maggot Damage

• Root maggots eat a plant's roots, which can kill the plant or stunt its growth.Ryan McVay/Photodisc/Getty Images
  
  Root maggots can stunt the growth of a host plant by preventing the roots from branching out. They also can cause the plant to wilt, especially during the heat of the day, because roots whose growth is inhibited by root maggots cannot find more water or nutrient sources. Additionally, root maggots can kill the plant by eating its taproot, which is the main root that digs into soil, anchors the plant and provides it with the most water and nutrients. Moreover, when a root maggot tunnels through a plant, it compromises the plant's structure by producing openings for disease and rot.
  
  

Root Maggots and Marigolds

• While repellents and pesticides are available for controlling root maggots, marigolds offer an effective, chemical-free and environmentally friendly alternative. Marigolds repel harmful insects naturally in two ways. The first way is through their scent. Marigolds generate a strong odor that root maggots in their adult fly stage find offensive, which will prevent them from entering the garden. (As a bonus, some beneficial insects, such as ladybugs, find the scent attractive.) The second way that marigolds repel root maggots is by producing an essential oil that is lethal to root-eating insects.
  
  

Maximum Control

• You might need many marigolds to be effective in controlling root maggots. Simply planting a marigold next to a vulnerable plant won't be enough. Ideally, you should give the plant bed a season off from crops and plant marigolds instead. Then, next season, plant as usual in your garden, except do so using the marigolds as "companion plants" for your crops.
  
  

Marigold Growth and Care

• To grow marigolds, plant seeds approximately 6 or 7 inches apart to ensure that they have enough room to grow, cover the seeds with loose soil and water thoroughly. They are very tolerant of hot weather, germinate quickly and begin blooming in around two months. To maintain the marigolds, prune them as needed, keep their space weed-free and fertilize as instructed on the seed packet.