Phytomyza gymnostoma
genus Allium leafage mineworker are devastating pests of garlic , onion , shallots , chive , and Allium porrum – and can destroy an full crop .
These encroaching insects are spreading rapidly throughout the mid - Atlantic and northeastern regions of the US .
Learn how to control then destructive pest with this guide .
Photo via Alamy.
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In December 2015 , bucolic Lancaster County , Pennsylvania , was the fix of the first confirmed infestation of the invasive allium leaf miner in the US .
Since then , this interloper has continued its inexorable border district throughout Pennsylvania to Maryland , New Jersey , New York State , Massachusetts , and as of other 2020 , Connecticut .
Photo via Alamy.
As its name suggests , this pernicious plague attacks high - economic value commercial-grade crop likeonions , garlic , Allium porrum , chives , andshallots , as well as wild and ornamentalAlliumspecies .
It can totally destroy an allium harvest and have marvelous losses for commercial-grade and base growers alike .
The genus Allium aka onion leaf miner is a particular threat to organic and domicile gardener , since they do not routinely treat their crops with synthetic insecticides .
agriculturist are highly concerned that this pestilence may transmigrate to the westerly US where onion are a major commercial-grade crop .
As Cornell bugology professorBrian Nault told the Cornell Chronicle , “ this has been a huge concern ” for Allium cepa grower .
In this article , we will cover the biology and recognition of these pest and the control measures that you may use to fight back against an plague :
What You’ll Learn
What Are Leaf Miners?
The allium leaf mineworker ( ALM),Phytomyza gymnostoma , is a genuine fly in the Agromyzidae family .
Native to Poland , this little fly front had spread to 21 country in Europe and two in Asia before it turn over the US .
The US already has twonative leaf minersfrom the same insect family that can infest allium metal money . They admit the American serpentine leaf miner , Liriomyza trifolii , and the vegetable leafage miner , L. sativae .
These native species are much less of a terror to allium crops as they cause very little damage .
This is in part because theLiriomyzaspecies are native to the US and are likely to have acquire with a raft of natural enemy that help oneself to keep their population in bridle .
Typically , invasive insects from other part of the world pose a much greater threat to crop , because they have no rude enemy in their new area .
In addition to the ALM , there is another invasive leaf miner – that also assail alliums – spreading throughout the northeastern US .
The larvae of the leek moth , Acrolepiopsis assectellaare caterpillars that are visible on the leafage surface . These insects are members of the Acrolepiidae class and can well be distinguished from ALMs .
The term “ leaf miner ” refer to the wrong that the insects cause on plant rather than to their taxonomic classification .
The larvae of many eccentric of flies , butterflies , moth , and bees can live inside industrial plant leave-taking where they feed as they mature .
They bear into the bulbs , stem , and foliage and the damage they cause manifests as tunnels that look like fickle lines on the parting as they jaunt to feed . Different types of leafage miners can cause vary pattern .
In addition to the lineal damage they cause , these alimentation tunnels can be colonize by fungus or bacteria , such as those that cause soft rot . These secondary infections can cause the plants to rot and buy the farm off .
Identification
The grownup ALMs are flyspeck flies of about an 8th of an inch long .
They are gray or black , and can be identified by the classifiable orange or xanthous eyepatch on the front and tops of their heads . The tent-fly are disgraceful behind their centre .
The sides of their abdomens and “ knee joint ” are also yellow .
If you look closely , you may see pane under their vindicated wings , which sit down horizontally over their abdomen when the flies are at residual .
The tiny eggs are white and somewhat curved . They are hard to see with the naked optic .
The headless larva , or maggots , can be xanthous , ointment , or white , and are up to a third of an inch long .
The pupae are a decisive point for recognition , since the flies can pupate inside the shank tissues but remain visible to the au naturel optic . The oblong pupa are about 0.15 of an inch long and carmine to dark brown .
It can be unmanageable to differentiate the adults of allium leaf miners from other species of fly sheet , as they are so tiny . expert tell them aside by dissect them under a microscope .
Biology and Life Cycle
ALMs have two generations a year . The first emerge in the spring from pupa that have overwintered in the root , bulbs , or soil .
After the eggs have hatched and the larvae have tunneled through your precious alliums , eating their filling , they pupate and get down the cycles/second again .
The grownup flies feed on the sap of allium go away . Before she lays her eggs , a female fly will make holes in the leafage using herovipositor – the retentive tube that is used to posit eggs .
She will make a large telephone number of punctures , which face like a serial of modest blank spots in a one-dimensional blueprint on the top of the foliage airfoil .
Both manful and female flies feed on the sap that exudes from these damaged area , and the females will come back to lay eggs in the puncture mark .
The females lay their bollock approximately a week after make the punctures . The egg mass on the leaves look like a course of brown dots .
The adult fly that egress in the spring typically lay their eggs over the course of four to five weeks .
After the eggs hatch , the larvae burrow through the leaves , eat their fill as they make their way towards the root .
It ’s this feeding that bring out the characteristic trail of a foliage miner . These trails widen the closer they get to the stem , as the size of it of the maggots increases .
The mining and alimentation make the plant life tissue paper to moderate , increasing the susceptibleness to bacterial and fungal infections .
When they have reached the base of the leaf or the bulb , the larvae pupate – there can be up to 100 pupae on each plant .
you could typically see the pupa at the base of the plant or on the surface of the soil nearby until the declination .
Then , the next generation of adults emerge from September through November and lay testis for five to seven weeks .
The pupae form from this contemporaries overwinter until the spring of the fall out year and emerge from March through May .
Organic Control
Dr. Gladis Zinati , Director of the Rodale Institute ’s Vegetable Systems Trial , and colleagues , conduct two - twelvemonth tribulation to find which method can beused to verify the ALM .
They found that immix multipleintegrated pest management(IPM ) tool can reduce crop loss from these pests .
As they are a comparatively novel reaching on US shores , research is still ongoing to square up the best way to look at with them .
Most of the inquiry is typically focalize on commercial-grade raiser rather than home gardeners , but we can peck up some crown from what the pros do to head off crop red ink .
To get down with , you postulate to ground that you are actually treat with the genus Allium leaf miner and not some other case of insect .
Monitor the Populations
As it is the larva that have the most damage , it makes common sense to take dance step to protect your crops during the time that the females are most likely to be laying eggs .
But how would you know that they ’re around ?
Sticky yap are often used to identify the presence of blighter , and these can be deployed in your garden to supervise what worm are hang around your vegetable patch .
Dr. Zinati ’s team receive them to be a useful tool as described in a 2020 article in the Pennsylvania newspaperLancaster Farmingwhere she mentions that the use of chicken glutinous traps is far more good than using blue ones .
The traps should be placed in late winter or former spring and checked on a regular basis to identify which pests are visiting your garden . you may keep them in place throughout the mature time of year , or replace in late summer to monitor the mien of the second generation .
Yellow Sticky Traps
you’re able to chance yellow sticky trapsavailable from Arbico Organics .
Other ways to monitor the presence of these insects admit looking for the marks produced from oviposition on the leaves . These are typically the first indication that your flora have been infested .
You should also look for leaves that are curly , wavy , and distorted – although this typically bechance later in the time of year , after the larvae have had a chance to do extensive damage . The other leafage miners that attack alliums do not cause this symptom .
by and by in the growing season , you could pull plant life that are exhibiting symptoms out of the priming coat and draw out the leaves back to crack for pupa .
If you think that you may have an infestation of ALMs , you may send in your glutinous hole toyour local reference agentfor a professional diagnosis .
Floating Row Covers or Insect Netting
If you are growing your allium crops in a particular localisation for the first meter , you could usefloating quarrel coversor insect netting to protect your crops from these insect .
It is critical to site them over your plant before the adult fly are active , either in the springiness or early downslope .
You ’ll need to leave them in place for at least four to six weeks to preclude the flies from position nut in the foliage .
It ’s a good idea to invest sticky traps inside the quarrel covers to check over that none of the pests are finding a way in .
Unfortunately , floating quarrel covers will not work on areas of your garden that were previously found with alliums , since the insect can pupate in the soil . Then , the grownup insect would be trapped inside with your craw !
Sources of the worm also admit the hazardous onion grass that could be growing in your garden .
If you see more than one or two plant with ALM equipment casualty , it is plausibly too late into the flight season to be able to apply quarrel covers .
Plastic Mulch
Dr. Zinati and colleagues compared onion plant grown with differently colored plastic mulch compared with bare ground to see what effects it had on the horizontal surface of infestation .
They found that there was very petty terms from the leafage miners when black or brooding argent charge plate mulches were used . Red credit card did not do work as well .
Unpublished research by Cornell University entomologists Grundberg and Rusinek , which was present to the Eastern New York Commercial Horticultural Program in January 2021 , showed that silvery reflective mulch are 30 - 35 percent more efficacious at controlling ALM than black or lily-white mulches .
However , even with this level of control , the pests can still overrun the crops .
All is not lost , however !
Plastic mulches form well when combine with other technique , such as the exercise of Spinosad , as part of an IPM program .
Spinosad
Spinosad is an organic insect powder derived from the fermentation of certain bacteria .
Drs . Nault and Fleischer found that apply this product to the roots of organ transplant onions , green onion , and Allium porrum or to the territory in hack trays for plant life starts reduced the amount of price by 90 percent after transplant .
Grundberg and Rusinek conclude that the combination of a reflective mulch with two applications of spinosad combine with the horticultural soap M - Pede , available on Amazon , can reduce the wrong to satisfactory floor so that the alliums could be sold commercially .
M - Pede Insecticidal dressed ore
The combination of these two techniques was by far the most effective organic ascendence method for the flies .
For the home gardener , spraying your plants with Spinosad at the first sign of plague can limit the damage sufficiently to let for a successful harvest .
Monterey Garden Insect Spray
you may corrupt OMRI - certify Spinosad in the descriptor of Monterey Garden Insect Spray , available from Arbico Organics .
Spray both the upper and lower surface of the leaves . If you see continued damage , take over the program . you could do this two or three times throughout the time of year as require .
Do not apply more than five times a class .
Cover Cropping
Dr. Zinati found that growing a mixture of tillage radish , mustard , and rapeseedas a cover cropbefore growing white-livered onions significantly reduced the numbers of ALMs .
Several factors appear to be involved .
One is that these plant fromtheBrassicagenusadded sulfur to the soil , which was absorbed by the onion plant and increased their bite . The folio miners appeared to target onion that were less pungent .
The yields in onion plant that follow this screen crop were twice as magnanimous as those that followed a screen crop mix of lily-white Dutch trefoil , helianthus , rye , and hirsute vetch .
The reason for this was that the non - brassica screen crop had more than double the numbers of mycorrhizal fungi , which increased the amount of atomic number 7 available to the crops , which increased their appeal to the leaf mineworker .
And excitingly , onions have a full storage lifespan when there is more sulfur in the soil .
bump our suggested cover craw selections here .
Cultural Methods
One scheme can be to expect to plant your crop until after the ALMs have finished laying testicle . This timing will depart based on your location .
Avoid fertilizing with atomic number 7 excessively , since that can increase the degree of folio miner infestation .
Keep your plant well irrigate to slim their levels of emphasis . This will allow them to resist off secondary infections that can lie in waste to your integral crop .
Rotating your crops is always good gardening practice , and habitation gardeners have more opportunity to do this than turgid commercial growers .
practice good sanitation at the end of the growing season is vital for controlling these fly sheet the next season . It is important to free your garden of ALM larva and pupae . off all plant debris and dispose of it in the trash , not on your compost big money .
To be absolutely sure that you have removed all larvae and pupae , your best wager is to burn the infested tissue – if that ’s permitted in your locus – or bury it as deep as possible and solarize the stain by placing clear plastic over it .
Biological Control
Unfortunately , the coarse strategy of apply good nematodes to the soildoes not operate in the case of leafage miners .
However , the parasitical waspDiglyphus isaealays its eggs on the larvae of all foliage miners in the Agromyzid category and kills them .
Technically , these types of WASP are known asparasitoids .
This character of discourse works best if the wasp are released too soon in the season before the grownup ALM universe build up .
Diglyphus isaeaParasitic Wasps
These parasitoids can dramatically lower the populations of leaf miner , but they will not provide entire control . They should be used as part of an IPM scheme .
you may buy these waspsfrom Arbico Organics .
inaugurate the wasps on two separate juncture , a week aside , and repeat in time for the second propagation in nightfall . twice
If it is hot and cheery , it ’s recommend to release the wasps early in the day or in the previous good afternoon or early evening .
Chemical Pesticide Control
As described in the journalEconomic Entomology , Dr. Nault ’s research squad tested various control criterion on onion , green onion , and leek in New York State and Pennsylvania .
chemical substance insecticide were found to be extremely effective at carry off ALMs and reducing their damage .
efficient synthetic insecticides available to homeowner include abamectin , imidacloprid , and cyfluthrin .
Abamectin Insecticide
you’re able to find abamectinavailable from Amazon .
Apply to the foliage when you first remark the leaf mineworker . hold back seven days and then reapply .
After two app , you should turn out to a different type of insecticide .
hold off 30 years after app before reap your onion , garlic , or other types of genus Allium .
And always remember to take adequate guard when youuse chemicals in your gardenand always follow the producer ’s directions .
The Threat Is Real
genus Allium leaf miners are plague that are highly destructive to high - time value crops likeonions , scallion , chives , garlic , andleeks .
These insects are impinge in the mid - Atlantic field and have spread north to Massachusetts and Connecticut .
Even if you do not subsist in these locales , you should be mindful of the possible spread of this insect into your area and take forethought to protect your crop .
And for more selective information aboutgrowing alliumsin your garden , contain out these guides next :
© require the Experts , LLC . ALL right wing RESERVED.See our TOSfor more item . mathematical product photograph via Abamectin , Arbico Organics , Gowan , and Monterey . Uncredited photos : Shutterstock . With additional writing and editing by Clare Groom .
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Helga George , Ph.D.
