I’m being obstinate, but I won’t stop eating leeks. The allium leaf miner is a bothersome creature that has settled here and enjoys eating anything from the allium family, however it seems to have a special fondness for garlic, leeks, and bulbing onions.
Leeks and garlic I can’t bring myself to give up, but I’ve given up on onions. From March on, I cover everything I cultivate with a fine mesh netting. Overwintering leeks are extremely sensitive because the leaf miner lays its eggs twice, in March and April, and then those eggs hatch and deposit eggs in October and November. Being only 3mm long, it frequently squeaks through gaps and crevices to reach its offspring’s favorite meal. Garlic can endure, but I find the leeks are frequently in shambles and decay during the winter.
I’m going to try something new this year. I’m getting smaller and leaner. Leeks will be successively sown, and I’ll pick them when they’re just a little bit bigger than my thumb. Regardless of miners, this is a great trick for small gardens: you can cram a lot of tiny baby leeks where it would be impossible to fit mature ones, and they taste divinely delicate with no trace of harshness.
Leeks germinate best in soils at 10-15C, so I’ll sow them in situ from the third week of April through June. I’ll sow them in wide drills, aiming to have the seed 1cm apart, with 15cm between rows, rather than sowing them now for transplanting out just as the miner is on the wing. When the leeks are 15 to 20 cm high, I’ll harvest them (after about 13 weeks).
Ideally, I won’t see many flies, but even if I do, any infestations will be removed before the second generation can establish themselves. Of course, you can start growing leeks indoors now and start enjoying them in June if you don’t have leaf miner. Pick early, quickly developing types like “Nipper,” “Bulgaarse Reuzen-Lincoln,” or “Sprintan” F1.
You don’t have to stick to baby leeks; when plucked young and sweet, beets and turnips are even better. The seed should be spaced 2.5 cm apart in rows 20 cm apart, or 5 cm apart in patches or blocks. For excellent little beet and turnips, space them 7.5–10 cm apart. Within 9 to 12 weeks, you should have roughly 30 plants per 30cm2 that are ready for harvest. Giving them a little more room, say 15 cm between plants, will encourage very quick growth.
Are there pests on leeks?
The Allium family of plants, which includes onions, garlic, leeks, chives, and shallots, is plagued by the leek moth. The larvae feed on crop foliage, which stunts plant growth and shortens the crop’s shelf life.
2009 saw the first US discovery of the leek moth in a garden belonging to a Plattsburgh, New York, resident (Clinton County). The first instance of this bug, which is native to Europe, was recorded in North America in 1993 in Ontario, Canada.
Allium leaf miner: what is it?
The destructive allium leaf miner can wipe out an entire crop and is a pest of garlic, onions, shallots, chives, and leeks.
The mid-Atlantic and northeastern US regions are seeing a rapid proliferation of these invasive insects.
For you to find pertinent products, we provide links to sellers. We might receive a commission if you make a purchase through one of our links.
The quaint Lancaster County in Pennsylvania was the scene of the first known infestation of the invasive allium leaf miner in the US in December 2015.
Since that time, this intrusive force has advanced relentlessly through Pennsylvania, Maryland, New Jersey, New York State, Massachusetts, and, as of early 2020, Connecticut.
As implied by its name, this noxious pest preys on wild and ornamental Allium species as well as high-value commercial crops like onions, garlic, leeks, chives, and shallots.
It can completely ruin an allium crop, resulting in enormous losses for both commercial and household gardeners.
Given that they don’t regularly spray their crops with synthetic insecticides, organic and home gardeners are particularly at risk from the allium, also known as the onion leaf miner.
Because onions are a significant commercial crop in the western US, growers are extremely afraid that this pest may migrate there.
This has been a major problem for onion growers, as Brian Nault, a professor of entomology at Cornell, stated in the Cornell Chronicle.
What is UK consuming my leeks?
Although the leek moth is primarily found in southern England, it is beginning to spread north. It is less common than the allium leaf mining fly. The foliage, stems, or bulbs of vegetables like leeks, onions, and allied plants are where the caterpillars feed.
What causes leeks to have brown streaks?
Examine the leeks growing in your vegetable patch. Do some of them have dots or streaks on their leaves that are brownish orange? If so, rust might be present. Leek Leeks, onions, and garlic all have leaves that can develop rust, a fungus that is widespread, especially at this time of year.
Don’t give up if you notice leek rust on your leeks. Leeks can still be harvested and prepared. Just pull the damaged leaves off before washing and chopping them. If they aren’t quite ready to harvest yet, you can remove damaged leaves from the plants (while taking care not to let them fall to the ground) and give them a good watering. Just water the plants at the base; avoid getting water on the foliage. Hopefully they will develop further without becoming too infected.
One thing to keep in mind is that other leeks are quite likely to contract the infection if you leave any contaminated leaf on the ground. They can be composted, but be sure to do so far from your bed of leeks. Alternately, burn them at the bonfire the following week!
In the future, we advise the following three steps:
- Leeks should not be grown in soil high in nitrogen. Nitrogen can make plants more vulnerable by softening their leaves. If you apply manure in your garden, you might discover that the nitrogen content of your soil is rather high. If you want to grow leeks, try using a multipurpose compost instead.
- Allocate a little more room for plants. By allowing more air to circulate around and inside the plants when they are planted too closely together, you can reduce the likelihood that leek rust will attack your plants.
- Consistent soil moisture should be maintained. Leek rust is made worse by protracted dry periods followed by copious amounts of rain. Keep things as level as you can, though it may be harder this year because of how dry it has been.
How is allium leaf miner treated?
The only practicable method of control is to cover the crop with insect protection mesh or fleece, particularly during the risky months of March through June and September through November.
If the infestation is found in the crop, the infected plants need to be uprooted right away and destroyed. Avoid composting infected plants since the pupae can still hatch and spread the virus.
Inform your neighbors who are producing veggies next to you or on an allotment about the issue and how to solve it. At the very least, this will lessen the hazard and fly population.
Miner damage to allium leaves
Track marks in the leaves and distorted, crumbling leaves.
Traces of an allium leaf miner in harvested leeks
We appreciate Stewart Jones for the image
Check your plants regularly
Check young seedlings frequently for leaf mines, especially if leafminers have previously damaged your garden. On the first genuine leaves, mines are most prevalent.
Vegetable leafminers are typically under control thanks to their natural enemies, therefore management is not necessary.
When spinach leafminers attack the leaves of a root crop like beets, no treatment is required. On spinach or another leafy green, however, management may be required.
Keep your garden clean
- Eliminate weeds like lambsquarter to lessen leafminers’ access to it as a feeding source.
- When the mines are small, remove and destroy the leaves.
- After harvesting, till your garden to kill pupae and lessen the possibility that adult flies may move to nearby plants.
Use a physical barrier
- Row covers made of fine-mesh netting should be installed to protect the plants from insects.
- Utilize materials that allow sunlight and rain to reach the plants (e.g. cheese cloth).
- Apply where there haven’t been leafminer issues for at least a year.
- This netting won’t assist if leafminer problems have been noticed during the past year since pupae that survived the winter are inside the row cover and can still infest plants.
- Row coverings are available from numerous neighborhood lawn and garden supply businesses as well as online vendors.
Using pesticides
When pesticides are used, adults are prevented from producing eggs, but larvae that are already eating inside plant leaves are not killed. Select a pesticide with a low environmental impact that does not harm pollinators or natural enemies like parasitic wasps (such as bees).
- Spinosad is an option that may work well. It provides effective control and has little effect on natural enemies because it is generated from a bacterium that lives in the soil naturally.
- Permethrin, bifenthrin, and carbaryl are examples of broad spectrum insecticides that can kill both pests and their natural enemies.
- When adult flies first become active in the spring, insecticides can be used.
- Make sure the leaves are adequately covered.
- Apply a number of treatments on a regular basis (check the label to determine how often you can apply a particular product).
AVOIDANCE: Any mention of a pesticide or the usage of a pesticide label is done so purely for educational purposes. Always adhere to the instructions on the pesticide label on the container you are using. Remember that the law is on the label.
Make sure the vegetable you want to treat is specified on the pesticide’s label before using it. Keep track of how many days pass between applying pesticides and the crop’s ability to be harvested.
Suzanne Wold-Burkness, from the College of Food, Agricultural, and Natural Resource Sciences, and Jeffrey Hahn, an entomologist with Extension
What is going after my leeks?
A This pest, which was hitherto restricted to the south and east coasts, is now spreading far and wide. The leek moth, Acrolepiopsisassectella, is small and unremarkable as an adult, but the caterpillars are the ones you need to watch out for since they cause the most harm.
A The leek moth is typically described as a regional issue that solely affects the south and east coasts, although it is now spreading north and west and has been observed in north Wales. It is readily available throughout Europe.
A The yellow-green caterpillars have fleshy pro-legs at the back and front, a dark head, and dark elevated patches covered in hairs. Upon hatching, they are 1mm long and eventually reach 10mm. The pupa is 10mm long and is encased in a silk cocoon that is cream in color. The moth is 8 to 9 mm long, grey-brown in color, and almost distinct from many other little moths that look alike.
A Leek moth can attack chives, garlic, onions, and shallots in addition to leeks, which is what you might expect given its common name as a pest of leeks.
A In the UK, there are two generations of caterpillars each year, in late summer and spring. The initial attack is frequently mild, especially following a chilly winter. The second one is the most harmful, and hot summers often make the insect more prevalent and the issue worse.
A Like leaf miners, the immature caterpillars make brownish-white patches by tunneling between the leaf’s surfaces. As they grow, they penetrate deeper into the leek or onion bulb, inflicting more serious harm and letting rotting fungi and bacteria inside. The vegetables typically get slimy and sprout yellow leaves at this point.
A Commercial producers rarely encounter this issue because pest management measures for other pests usually take care of it. But unless adequate preventative measures are implemented, it can make growing leeks and onions very challenging for gardeners and organic growers.
A new pest that is already dispersing from the West Midlands, the Allium leaf miner, can produce a comparable result by destroying leaves and promoting rot. The leaf-miner pupae are orange-brown without a silk cocoon, while the larvae are off-white with no legs and an obvious head, resembling maggots.
In addition to rotting at the base, onion-fly damage can also cause yellowing of the leaves and maggot clusters in the base of the onion or leek.
A The plants should survive if the caterpillars can be removed while they are still in the mining stage. Leeks, in example, can withstand pretty serious damage to the upper sections to give at least some crop.
After being assaulted in the lower portion, the plant will likely die from secondary rotting.
Unharmed sections can still be consumed, but make careful to squish any caterpillars and pupae on fallen leaves. It is better to deeply bury or donate severely damaged plants to your local council’s composting program.
A Every year, there are two generations. In plant detritus, adult moths overwinter before emerging in the spring to lay eggs in April and May.
After hatching, the caterpillars consume the leaves for nearly a month as they move steadily downward toward the plant’s base. They climb back up to the leaves to pupate after they reach adulthood.
The second generation of caterpillars causes harm from August to October after these pupae hatch and pupate. Even while some of these pupae might not hatch until spring, the majority do so before winter.
A Covering your crops is the best approach to keep this bug away from them. Horticultural fleece can be used in cold weather, but in the summer it can make crops excessively hot and prevent much rain from penetrating, therefore insect-proof mesh is preferable.
After harvesting the plants, remove all plant debris. Additional management techniques include excavating the soil to disturb and expose overwintering adults. For this pest, there are no insecticides that have been licensed for home use.
Eggs can be found on stems, and if the stems are not effectively removed, the eggs will hatch and infest fresh crops. Willow-carrot aphids are commonly seen on leftover parsley, parsnips, and carrots in the spring. Prior to May, these overwintered root crops must also be thoroughly composted.