We help gardeners with gardening questions.

For more information on Pests & Diseases scroll past the Questions section.

Q&A: Pests & Diseases

• Infestations of white flies
• Controlling red lily beetles
• About the blister beetle
• Asian ladybug and woodpecker issues

Question: Infestation of white flies 

I seem to have an infestation of white flies on my tomatoes, beans as well as flowers. I have tried to eradicate the problem with vinegar, water, soap, and baking soda. I still see loads of eggs and flies throughout my garden. What can I do?

Answer:
The problem seems indeed a severe infestation of white flies and their immobile nymph stages, not eggs. The life cycle of this insect lasts over 40 days and needs constant monitoring at the five different stages as some can be controlled with insecticidal soap while other stages cannot. Various products such as neem oil, which is not a registered safe product in Canada, and pyrethrins, which are not good for use close to food products, ie vegetables, are often used but the MMGA does not recommend using any such control methods other than insecticidal soap. There are two links at the bottom of this email which includes all the various stages and how to manage.

The problem you are experiencing seems to be so heavy for the plants that you describe, which are shriveling, that the recommendation is they be pulled and the plants solarized in clear plastic bags in the sun for several days before they go into the garbage. This method is certain to eradicate those various stages of the whitefly.

For any remaining plants the suggestion is to remove the heavily infested leaves and for the remaining plant leaves, continually, every 5 days or so, spray with insecticidal soap on the leaf undersides but not in the heat of the day.

Whiteflies do not survive over winter in Manitoba. The ones that are in your garden have come through greenhouse plants that you have purchased. Always be sure to check greenhouse plants before purchase to be sure no whiteflies are attached to it. Shake the plant and brush it to be sure no cloud of these insects appear. Also, practice preventive and management measures such as not planting succession crops that are host plants like kale, lettuce.

There seems to be disease and insect problems this year, 2023, that are more prevalent than in other years so hopefully this could be the case.

https://extension.umd.edu/resource/whiteflies-vegetables
https://chemung.cce.cornell.edu/resources/whiteflies

Question: Controlling red lily beetles

I had so many of these beetles this summer. They destroyed all of my lilies. I did use some powder insecticide, that helped for a while, but they ended up destroying all of my lilies anyway. Do you have any suggestions about how to get rid of them?

Answer:
This is the red lily beetle and it is very difficult to control. The methods to control red lily beetles: hand pick and destroy each beetle, all the eggs, and the larvae. Either squash the beetles or drown them in a bucket with a solution of soapy water. Always check leaf undersides for the hidden eggs and destroy them by rubbing them off. The larvae of this beetle look like black blobs on the plant leaves. In reality, this is the larva covered in its own excrement. Destroy these too! The adults and larvae can be sprayed with any pyrethrum-based insecticide or any other registered pesticide. Buy a concentrated pyrethrum liquid and mix to 0.5% strength. Use all products safely and with care following instructions. Spraying or dusting with any product is not a cure for ridding these beetles, only a slight deterrent.
In the fall, clean up any debris (leaves, mulches, etc.) under the lily plants as the red lily beetle likes to hide and overwinter under such materials. Also, in spring and fall stir up the soil under these plants as the beetle likes to bury just under the soil surface. Hopefully, the cold temperatures will kill them.
All summer one must be vigilant as these beetles have a strong flying capability and can fly in from neighbouring gardens.

• For further red lily beetle information:

http://carleton.ca/biology/people/naomi-cappuccino/
Red Lily Beetle Tracker
Biocontrol of Red Lily Beetle

Question: About the blister beetle

This evening I discovered an insect I’ve never seen before. There were at least eight insects per small plant. I’ve had a caragana hedge for 40 years and never seen this kind of bug. I’ve attached a picture. It has wings. Any information you can give me would be appreciated.

Answer:
The insect in the photo is a blister beetle. It is quite common on caragana, and has both good and bad qualities. The larvae are predaceous, and have a taste for grasshopper eggs. The adults are herbivores and can be quite damaging to many crops, mainly canola. Damage to caragana becomes of lesser concern as the plant ages.

Question: Asian ladybug and woodpecker issues

I am experiencing way too many ladybugs (Asian biting kind). They are everywhere as well as on my ornamental apple tree. I have noticed that I have a woodpecker that has a big focus on that tree as well. I am wondering if there is anything I can do to get rid of these ladybugs and if that woodpecker is killing my tree. There are rows of holes in the trunk and the ladybugs are hiding in some of those holes. I would hate to lose that tree as it serves as privacy between me and my neighbour and it is beautiful.

Answer:
In fall it is quite common to see more of these Asian ladybugs, and yes they do bite, unlike our native ones which do not. They are looking for a place to overwinter and hence why they are going into these convenient holes. You are fortunate, as many come into homes through cracks and crevices and take up winter residence inside. Both lady beetles are beneficial insects devouring aphids, hence it is not recommended to destroy them. If they do migrate into your home vacuum them up and throw them into the trash. If you squash them they will give off a foul odour.

To answer your woodpecker problem, you say the holes are in rows, this is the sign of a sapsucker. The sapsucker drills these holes in trees so that they can access the sap and attract insects for the sapsucker to feed on. A very devious bird! It is difficult to keep the sapsucker away once they have been attracted to your tree. Some people have been successful hanging shiny objects from tree branches; CDs, reflective tape or pop cans. Sadly, if the sapsucker continues to do this damage to the tree, the tree will succumb after a few years. If the holes are random this is a sign that the bird is a woodpecker. Woodpeckers attack trees that are in their demise and not healthy. They are attacking insects that are in the tree.

Question: Severe aphid infestations

I have a golden ninebark, which to look at is otherwise very healthy, but it has a lot of tiny black eggs or bugs on some leaves and branches (this also happened last year), and also some strange-looking larger bugs I have never seen. I assume these are what are laying the eggs, but there are also a lot of ladybugs on it right now. Last year I just cut the branches with the eggs off, but never saw these other bugs anywhere. Is there something I should/could do to prevent this in the future? Preferably with a safe remedy over harsh chemicals if possible!

Question: Identifying beetle-type nymphs

Thousands of tiny beetle-type nymphs have erupted in my garden wood chip, dark with a small horizontal red strip close to the top, long antenna, hops like a cricket, and maybe can fly. Any idea what they might be, good or bad?

Answer:
When they say a picture is worth a 1000 words, it probably is 10000 words for insect IDs. The latest photo is the nymphal stage of field crickets. Nearly every prairie gardener comes across these insects in late August but in their much larger black adult form. In many respects these insects are like the blister beetles in that they have both predaceous and herbivorous stages. The adults are the predaceous stage this time, and grasshopper eggs are also on their menu. The nymphs have a very diverse diet, and usually do not cause much damage to plants. Gardeners can minimize the presence of this insect by keeping their garden sufficiently watered.

Question: Cutworms on the prairies

I have noticed evidence of chewing on some of my flowers/plants.  It is not rabbits or slugs.  What could be causing these irregular holes?

Answer:
This damage could be caused by the type of cutworm. There are several species of cutworms on the prairies. We are most familiar with the ones that cut off our bedding plants or young seedlings at ground level. These do most of their damage in May or early June. The climbing cutworm comes later and climbs up the plant at night and feeds on the foliage.  Along with chewed leaves being a sign of their presence, black grains of excrement are often found on the plant’s leaves. All cutworms can be found just under the soil near the damaged plants. They are usually dull grey and curl up into a ‘C’ when disturbed. You may occasionally find the climbing ones on the foliage. The quickest way to eradicate them is to find them and destroy them.  Other methods include putting barriers into the ground around newly planted specimens or spreading a coarse material such as crushed eggshells or diatomaceous earth around susceptible plants. Become familiar with the pupae and adult stages of the cutworm so that you can control them in those stages. Also, use preventative methods such as digging up the soil in fall and/or spring to expose the pupae or larva.

Question: Preventing worms in apples

I would love to know how to prevent little worms in my apples, is it too late to treat the apple trees and what should I do?

Answer:
If the buds on your apple tree have not broken, April is the time to spray the entire tree with a Dormant Spray kit. This kit can be purchased at any good gardening centre or greenhouse. It is compulsory to not have the buds broken and to spray when the temperature is above 0c. The temperature can be 0c overnight but when you are spraying it must be above.
Also, refer to the answer below for summer treatment.

Question: Eliminating apple maggots

I have a very prolific Heyer apple tree which has become infested with apple maggots. The entire crop over the past few years has been of no use, riddled with brown tunnels, and now the problem has begun to spread to a delicious Goodland apple in my yard. I kept red sphere balls coated with Tanglefoot on the south side as of June, diligently removed all fallen fruit (25 pails of it) did not compost it, and searched for all shrivelled apples remaining on the tree in the spring. Do you have any other solutions? (non-chemical)

Answer:
You are certainly doing the correct procedures to eliminate the apple maggot problem. The suggestion would be to continue doing exactly the same non-chemical solutions. It will take a bit of time for you to notice a big difference but you should notice it this season. Put up the red balls covered in plastic wrap, cover them with the Tanglefoot and as it becomes overloaded with the insects, remove the plastic and throw it into the garbage.  Redo this method over the entire summer.

Question: Ant hills

I have ant heaps in my lawn. How do I get rid of them?

Answer:
Ants are very difficult insects to get rid of from lawns. A natural product that one can use is diatomaceous earth, a natural product composed of crushed sharp particles that cut the ant bodies. The process of eradicating ants would take a long time as the queen needs to die for the nest to be eradicated.

As much as people do not want ants around them, they are beneficial insects being scavengers and predators of harmful insects. When in the lawn they are eating larvae of insects that destroy the roots of your lawn. Ants do not damage one’s lawn, they only cause loosening of the soil and the formation of small hills.

Question: Damage from flea beetles and cutworms

Something invisible is making holes in the flowers and defoliating leaves from my pansies, both in the ground and in raised planters. We are on a small farm on Brady Road. Same in the Whiteshell, where I visited Red Rock Lake last month. What is it and how can I help the flowers survive?

Answer: 
The cause of this damage to your pansies could be several reasons, one of which is flea beetles. As you are in La Salle and close to canola growing fields, these beetles are quite common in these crops. They are small dark brownish-black sesame seed-sized beetles. This is not an easy bug to destroy. They disappear quickly and your plant will grow successfully in a short time. You could dust the plant and around it with diatomaceous earth or spray the plant with End-All 2.

Another bug could be a climbing cutworm that works at night. For this, you would notice black droppings, its excrement, on the leaves. If you suspect this insect, dig around in the soil at the stem and a bit further out first thing in the morning. It looks like a thick larvae and would curl up into a ball when touched.

Question: Impatiens Downy Mildew

I’ve been hearing recommendations not to plant  Impatiens because of an incurable blight that’s become an issue over the past few years.  I certainly saw lots of Impatiens in the garden centres but I’m wondering if we here in Manitoba are also going to need to start looking for alternative plants.

I’d appreciate any insight on this that you can offer!

Answer:

This disease is called Impatiens Downy Mildew (Plasmopara obducens) and is a fungal disease transported through spores.  It was first noticed in England approximately 10 years ago and has since travelled to North America and first noticed in 2004.  The disease was well managed until a severe outbreak in 2011 and then it travelled quickly between states.  From a posted map it has been identified in North and South Dakota.   It has also been identified this year, 2015 in Winnipeg and possibly other Manitoba areas.

The disease infects Impatiens walleriana, which is the common most popular Impatiens sold at greenhouses.  The new Bounce Impatiens, SunPatiens and New Guinea Impatiens is not affected with the disease.  It is suggested that these Impatiens varieties or alternative plants be used such as Browalia, Begonias, Coleus etc. 

Impatiens Downy Mildew is host specific which means that it only attacks one type of plant, in this case Impatiens walleriana and hybrid plants with this parentage.  It travels quickly and within 5 to 14 days the entire plant will be infected.  The plant one buys may be infected already as nurseries receive stock from distant suppliers or it will attack your healthy garden plant through spore dispersal, wind or water splash back.

If the Impatiens one plants is noticed to be attacked early in the season it will have been transmitted through systemic infection (plants received already infected).  This is called early season stunting.  If your healthy plant looks good until late in the season and then is noticed to have the disease it will have been infected through the wind/water situation.  Spores travel very far in wind and may come from the neighbourhood.  Early season symptoms are:  flower drop and bottom leaf curl and yellowing with the leaf underside powdery looking.  Late season symptoms are:  quick leaf/flower drop and green sticks/stems remaining.  This disease thrives in long periods of wet humid environments which were the 2015 summer’s perfect conditions.

All infected plants should be removed immediately and put into the trash not composted.  The spores can survive for a very long time in the soil where the infected plants grew.  Hence, Impatiens walleriana should not be planted in that area again for many years.

Question: Tiny worm on grapevine

This is a new problem with the grapevine tiny worm just to right of stem? Previous infestation of a skeletonizing caterpillar likely similar to tree leaf caterpillars. Removed all signs of caterpillars but now have these or something like Japanese beetle perhaps though have not found adult yet? Any ideas? Thank you

Answer:
Your problem seems to be as you mention, a skeletonizing worm. It has laid its eggs in between the layers of the grape leaves and now they have hatched as the tiny worms shown in your excellent picture. As the worms are emerging you could use BTK which is a natural product used for larvae/worms. They do not die instantly but after eating the sprayed leaves they will die. Be sure to clean up any fallen leaves and those in the autumn and throw them in the garbage not compost.

Question: Tiny white worms in raspberries

We have found tiny white worms in the fruit of our raspberries. What can we do now to ensure that this does not occur next year?

Answer:
What your raspberries are being affected with is the Spotted Winged Drosophila fly. Sadly this insect is a problem for many soft fruit growers and local gardeners. Here is a link to more information on our website: Click here scroll down until you come to the information.

Question: Bacterial blight in geraniums

I recently purchased several Martha Washington geraniums which unbeknownst to me were full of bacteria blight.  Two days after adding them to my window boxes I recognized the problem and discarded each and everyone.  Just wondering what I should do now.  Do I need to discard the other plants in the window box?  What about the soil and the container itself?  I should note that a container nearby also seems to be affected though it includes another species of geraniums from a different nursery.  Any information would be greatly appreciated.

Answer:

Xanthomonas campestris pv. pelargonii attacks only geraniums so if it is the true bacterial blight and the other plants are not of the Pelargonium x domesticum genus then the planters should be fine.  Nonetheless, you should be cautioned to not replant with anything from the Pelargonium x domesticum genus.

There is another disease Verticillium wilt, caused by a fungus, that looks a lot like Xanthomonas campestris pv. pelargonii and causes the same type of symptoms in many types of plants including geraniums.  There is no way (except by lab testing) to tell the difference between them.

Both diseases are soil born (from contaminated plant material).  The disease can be transferred through contaminated tools and/or soil splashback.  This could be the reason that your other container is also infected.  Remove these geraniums/pelargoniums.  The name Pelargoniums refers to all species of the well-known “geraniums”.  So even though the geraniums in the other box are different and had been purchased at a different nursery, if they are showing similar symptoms, they could have been infected through the previously noted way.  True Geraniums are the perennials that are usually grown in one’s garden.  They have small flowers in a variety of colours; whites, pinks and mauves.

The suggestion for this summer would be to remove all the geraniums/pelargoniums in your window boxes and bag them up putting them into the trash with none going into the compost pile.  This type of disease stays within the specific genus, hence not infecting other plants.  Do not plant any other geraniums in these boxes this year.

At the end of this summer the recommendation would be to remove all the soil, bagging it up and putting it into the landfill.  Sterilize the window boxes with a bleach solution and put in new soil.  Your tools should be sterilized too to prevent any further transfer.  By using infected tools in your garden the disease could be transferred into your garden beds.  Be careful to not plant geraniums in any of your garden beds if you have used said tools in them.   This type of disease can remain in the soil for at least a year or two.

Additional Information

Apoecilus nymphs

These insects are the nymphs of the predatory stink bug Apoecilus. There are numerous varieties of stink bugs. Some, like the Apoecilus, are beneficial, eating garden pest insects. Other varieties of stink bugs are garden pests that feed on fruit.

The Apoecilus nymphs can be mistaken for the more serious nymph of the brown-marmorated stink bug which is a nasty pest for many garden and fruit crops. Early feeding on apple crops can cause catfacing, while on strawberries and haskaps they cause fruit drop and bud death. The brown-marmorated stink bug is one of the most recent exotic pests that has arrived in Manitoba and could increase in numbers as our climate warms.

More info:
Apoecilus Nymphs
Brown Marmorated Stink Bug Nymphs

Forest Tent Caterpillar

The forest tent caterpillar egg rings around branches house approximately 300 eggs. Removing them through scratching off, being vigilant to not damage the bark, or pruning the branch with the egg rings on it, are excellent methods to control the worms before hatching. This should be done anytime one notices the ‘rings’ present. They are most noticeable when the leaves are off the trees/shrubs. Following is an excellent article from the University of Saskatchewan about forest tent caterpillars: Forest Tent Caterpillar

Mealy Bug

– appears as white fluffy areas around stems and leaf nodes especially on newer growth.
– related to scale insects as they survive by sucking on the plants juices/sap and they protect themselves by the fuzzy fluff which acts as a protective coating.
– the white ‘fluff’ is a waxy coating which resists water.
– to eliminate mealy bugs rubbing alcohol needs to be applied to these areas with either a cotton-tipped stick, cotton ball or from a spray bottle.
– if the mealy bug is not eliminated, overtime leaves will yellow, dry and drop off. Hence, no chlorophyll produced to support the plant. With severe infestation recommendation is to dispose of the plant.
– when the infestation is extreme the honeydew excretions from the bugs will drop and collect on leaves and cause sooty mould to form.

Black Knot Disease

Shubert chokecherry trees, plum trees, wild chokecherry and pincherry trees are susceptible to this disease. Early stages will show the black swollen growths on the branches and twigs. These must be removed a minimum of eighteen inches from the ‘knot’ towards the tree trunk and the pruners sterilized with each cut. The necessity of removing these are that the spores are formed in these growths. If left on the tree the spores will continue to infect trees of this variety. Once there are signs of infection in the trunk, which is manifested by cracking or splits, the tree will not survive and should be removed. Another such specimen should not be planted in that area or surrounding as the spores have a possibility of remaining in the soil and remaining roots.

Mealy Bug

– appears as white fluffy areas around stems and leaf nodes especially on newer growth.
– related to scale insects as they survive by sucking on the plants juices/sap and they protect themselves by the fuzzy fluff which acts as a protective coating.
– the white ‘fluff’ is a waxy coating which resists water.
– to eliminate mealy bugs rubbing alcohol needs to be applied to these areas with either a cotton-tipped stick, cotton ball or from a spray bottle.
– if the mealy bug is not eliminated, overtime leaves will yellow, dry and drop off. Hence, no chlorophyll produced to support the plant. With severe infestation recommendation is to dispose of the plant.
– when the infestation is extreme the honeydew excretions from the bugs will drop and collect on leaves and cause sooty mould to form.

Black Knot Disease

Shubert chokecherry trees, plum trees, wild chokecherry and pincherry trees are susceptible to this disease. Early stages will show the black swollen growths on the branches and twigs. These must be removed a minimum of eighteen inches from the ‘knot’ towards the tree trunk and the pruners sterilized with each cut. The necessity of removing these are that the spores are formed in these growths. If left on the tree the spores will continue to infect trees of this variety. Once there are signs of infection in the trunk, which is manifested by cracking or splits, the tree will not survive and should be removed. Another such specimen should not be planted in that area or surrounding as the spores have a possibility of remaining in the soil and remaining roots.

Spotted Winged Drosophila

Spotted Winged Drosophila Fly, male

The Spotted Winged Drosophila (Drosophila suzukii)  (SWD) is a vinegar fly of East Asian origin that can cause damage to many soft-skinned fruit crops.  SWD pierces seemingly healthy fruit, and lays its eggs.  The eggs hatch in about 3 days, the larvae feed on the fruit and emerge as adults after 6-28 days.  Early detection is critical because symptoms often do not appear until after the fruit is harvested.  Commonly confused with the common fruit fly, Drosophila melanogaster, SWD differs as it attacks unripe to ripe fruit, whereas the common fruit fly feeds on overripe and rotting fruit.

SWD most commonly afftects raspberries, strawberries, blueberries, cherries and plums.  It was first identified in Manitoba in commercial berry fields in August 2013.

DOWNLOAD .PDF >

For continued updated information on SWD follow this link:

www.gov.mb.ca/agriculture/crops/insects/spotted-winged-drosophila.html

Ladybug Larvae eating Aphids

An example of healthy biodiversity in the garden. This is a major reason to acquaint oneself with lady bug larvae and not destroy them.

Fall Webworm

This is an example of the fall webworm which appears in late summer or fall and how it manifests on common trees. The fall webworm is a tent caterpillar much as the forest tent caterpillar is. The most effective way of eradicating this worm is to prune off all affected branches from your tree or shrub and throw it into the trash.  If the branches are too high to prune hose the web with strong water pressure so as to break up the webbing and making the worms accessible to foraging birds.

Poison Ivy

Poison Ivy – in Autumn foliage