Do you know that root maggots are one of the garden pests where control is all about prevention?
It is important to note that once root maggots invade the soil and begin eating the underground parts of garden crops, there is not much you can do to get rid of them.
Getting a root maggot infestation under control as soon as possible is important because it makes vegetable inedible and can even kill the plants.
Plants that are weakened and damaged by these pests are more susceptible to fungal or bacterial infections.
These can include root rot and secondary infestations by other insects.
Moreover, root maggots are larvae of different species of flies.
Though common species such as onion maggot and cabbage maggot are named after their main host plant, they also tend to feed on numerous other vegetables.
It is important to note that infestations occur more commonly when the springtime weather is cool and wet.
Keep on reading.
What do Root Maggots look like?
Though the damage is done by the root maggots or larvae and not the adult flies for effective control.
It is, however, important to familiarize yourself with all the stages of the life cycle of the insect.
Life Cycle of Root Maggots: All root maggots species tend to share the same life cycle.
They tend to live for two or five weeks and go through three or more generations per year depending on the climate, the first one in late to mid-spring, the second in early summer, and the third in late summer.
Moreover, the small, red-brownish pupae of the root maggots tend to overwinter on the top, one to five inches of the soil, near the roots and debris of plants that were infested in the previous year or in the soil.
It is important to note that as the soil gradually warms up in the spring, adult flies tend to emerge over a span of four to eight weeks and instantly mate.
Two to seven days after emerging, the females seek out host plants to lay their eggs.
Preferred spots are often the base of host plants, in soil cracks and clumps of soil, or plant stems.
A female fly tends to lay over 100 eggs on a single plant over a couple of days.
After three to ten days, the larvae of the root maggot tend to hatch and immediately begin to feed, and burrow into the stems of the host plants, roots, root hairs, seeds, and any decaying organic matter.
It is during this two to four-week period that roots maggots will cause damage to your plants.
Once it is complete, they will evacuate their feeding grounds and move to the soil to pupate, remaining close to the surface.
After another two to four weeks, a new generation of adult flies tend to emerge and another life cycle begins.
The last generation in the late summer will remain in the soil where it overwinters as pupae to emerge the next spring.
Learn more about 9 Flower Garden Pests and How to get Rid of Them here.
The appearance of Root Maggots during Different Stages
The eggs of these pests are about one-eight of an inch, white, and oval.
The larvae that hatch from the eggs are about one-quarter inch long and yellowish-white to creamy-white in color.
Moreover, their legless bodies tend to be cylindrical-shaped without a distinct head.
The pupae are about the same length as the larvae and their oval bodies are enclosed in the hardened, red-brown larva skins.
The emerging adult flies tend to be about one-quarter inch long, slender, dark grey, or gray-brown in color.
They tend to be about half the size of the common housefly.
Signs of Root Maggot Infestation
How badly is your plant damaged by root maggots depends on the crop, its variety, and the age of the plant.
For instance, red cabbage is less susceptible to root maggots than green cabbage.
It is important to note that to the naked and untrained eye, it is often hard to distinguish the adult flies of the different maggot species from one another as they tend to look very similar.
However, their presence near host plants can give you the necessary clues.
Onion and Cabbage Maggot Damage: Onion maggots tend to feed on onions, leeks, garlic, and chives.
While cabbage maggots will feed on cauliflower, Brussel sprouts, radish, cabbage, broccoli, collards, kale, kohlrabi, turnip, other cruciferous vegetables, and in some cases, beets, and celery.
Moreover, seedlings and your plants tend to be most vulnerable while healthy older plants tend to survive moderate infestations.
A simple maggot can annihilate about 20 small seedings.
While in older plants, discolored, light green or yellow, and/or wilted leaves and stunted growth can be an indication that root maggots have already damaged the roots by boring a number of feeding tunnels into the underground stems, roots, and bulbs.
Root crops and bulbs like rutabagas are discolored, deformed, debris-filled, and have external scars, all of which make them inedible.
Also, infested cabbage, cauliflower, and broccoli plants do not form heads.
Eventually, severely damaged plants tend to die.
In case you suspect root maggots, you will need to pull up the plants and inspects their roots.
You will not necessarily see the maggots, only the tunnels, as maggots may have already moved on to the soil to pupate.
In such a case, you may see the reddish-brown pupae in the soil around the plant.
Seedcorn Maggot Damage: The seedcorn maggot and bean seed maggot also known as turnip maggot, tends to attack germinating seeds and seedlings of a wide range of vegetables.
This tends to include lima beans, peas, soybeans, corn, cucumbers, melons, squash, lettuce, spinach, cruciferous vegetables, and onions.
Moreover, these ones are harder to detect than onion and cabbage maggots as they tend to feed on the developing shoot before the seedling emerges.
You will only know which plants have a problem when seedlings do not emerge, they are only in greatly reduced numbers, or if they are damaged.
Causes of Root Maggots
The appearance of root maggots can be random, adult flies of root maggots have the ability to travel up to a mile to find suitable host plants.
In case you had root maggots in previous gardening years, they will likely appear again.
In addition to the above, there are three more factors that can foster root maggot infestation:
A coot, wet spring with temperatures between 6 and 79 degrees tends to provide ideal conditions for the root maggot eggs in the soil to hatch.
Moreover, the eggs cannot survive when the temperature in the top two to three inches of soil reaches over 96 degrees Fahrenheit.
It is important to note that root maggots are attracted by animal manure, green manure, and other partially decayed organic matter.
This does not mean that you have to forsake all the advantages that adding organic matter adds to your garden.
You will need to make sure that it is fully decomposed humus, so it does not offer root maggots anything to feed on.
Also, weeds in the cruciferous family, like yellow rockets, if they are growing nearby in substantial numbers also tend to bring root maggots to your garden.
The root maggots overwinter in the debris and roots of such weeds, then move to other feeding grounds in the spring.
Getting Rid of Root Maggots
It is important to note that once root maggots invade your plant to feed, there are no EPA-approved pesticides to get rid of them.
At this point, your only option is to remove the entire plants and destroy them.
Make sure to avoid leaving any infested plants in your garden.
This is because it can lead to an even heavier infestation in the same season or the next year.
The only way to control maggots is prevention as below:
Preventing Root Maggot
It is important to note that there is no single failproof method that will help to prevent a root maggot infestation.
With a combination of different methods, you can increase the chances of effective pest control. These are:
Floating Row Covers: Protecting susceptible vegetables with floating row covers is the best way you can prevent the adults from laying eggs and thus starting the entire infestation cycle.
In order to keep the cover in place, make sure to avoid crushing tender younger plants, as well as allowing for plant growth.
Moreover, it is best to set up the cover as a high tunnel and secure it with hoops.
Cover the vegetables from the time you seed or transplant seedlings in cooler weather until the onset of hot summer weather and again in the fall when the temperature gets cooler.
Root maggots tend to go through another cycle before the winter.
Thus, make sure that the floating cover is made of breathable textile and lets in water and enough sunlight.
Polyethylene covers are not suitable as it becomes too hot for the plants and the condensation can lead to foliage disease.
Crop Rotation: Crop rotation tends to be important in order to prevent root maggots, overwise the overwintering population in the soil will have an easy target.
As root maggots move around, it is not only imperative that you do not plant susceptible crops in the same spot as the year before.
However, also that you plant new crops as far away from the location of the previous year’s crop as possible.
Diatomaceous Earth: Spreading this around the base of the young seedlings and transplants will help to keep root maggots from attacking the plant.
You will need to apply it after each rain.
Planting Schedule: Adjust the planting schedule of susceptible crops to avoid root maggot peak times. It is another way to prevent an infestation.
Depending on your weather, delay planting until the end of May or the beginning of June when the soil is too warm for the eggs to survive.
Other Preventive Methods
Some other preventive methods are:
Raised Beds: The soil in raised beds tends to warm up faster and earlier, and will stay dry than in ground-level garden beds.
Planting susceptible crops in the raised garden will help create an environment that is less than ideal for root maggot eggs to hatch as they prefer cool, moist soil.
Garden Senition: thoroughly cleaning up your garden and removing any crop residues of all susceptible vegetables is important to prevent root maggots in the future.
Moreover, right after the harvest, dig out all the spent plants including their entire roots, and destroy them or dispose of them in the garbage.
Even if you do not find any root maggot damage, the plants should not e composted.
Till or dig up the area so any overlooked plants are exposed, as this will discourage the pupae from overwintering in the soil.
Make sure to monitor nearby areas for weeds in the cruciferous family which can serve the root maggots as host plants.
Also, remove them from their roots and dispose of them safely, the same way as any crop plants.
Biological Control: It is important to note that root maggots have a number of predators, including ground beetles, carabid beetles, and rove beetles, as well as different species of parasitic wasps that tend to attack the larvae and pupae.
Predaceous mites tend to consume the eggs and spides, male dung flies, yellowjackets, digger wasps, and birds tend to feed on the flies.
Moreover, parasitic nematodes and parasitic fungi also help to reduce root maggots.
However, these biological controls alone are not enough to keep root maggot populations under control.
Leave a Reply