PESTS & DISEASES

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We help gardeners by answering questions, contact us at ask@mgmanitoba.com

Q&A Topics
Infestations of white flies
Identifying beetle-type nymphs
About the blister beetle
Asian ladybug and woodpecker issues
Ant hills
Severe aphid infestations
Controlling red lily beetles
Cutworms on the prairies
Preventing worms in apples
Eliminating apple maggots
Deterring voles
Damage from flea beetles and cutworms

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: 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: 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: 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: 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!

    

Answer:
Thank you for sending the excellent pictures along with your questions. The first three pictures are of a ladybug transforming from the larva stage into the ladybug. They are a very good insect to have in your garden.
The last three pictures are aphids; definitely not a good insect to have in the garden. But ladybugs and aphids go together as ladybugs love to eat aphids. Nonetheless, this is a severe infestation that should be addressed. The best method is to take a hose and with as full strength pressure as the shrub will warrant, spray the aphids off the plant. Be sure to use a very strong water spray, especially under the leaves where aphids love to congregate. This water treatment can be done every couple of days until you notice a substantial loss of the aphids. They are very difficult to eradicate but this method works very well. Watch other shrubs in the area for them.

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.

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: Deterring voles

What do I do to deter voles from eating my trees, shrubs and hostas during the winter?

Answer:
With winter approaching voles will be a nuisance and very difficult to control. One can protect trees and shrubs by painting or spraying a product called Skoot on the bark. This product can be painted on tree trunks but spraying works better for the smaller shrub branches. This is a bitter-tasting product that deters voles and rabbits from eating the bark. It can be purchased at your local greenhouse or garden centre. Alternatively, if the tree is young with a small diameter trunk, plastic protectors can be wrapped around the trunk for the winter. Again can be purchased at your local greenhouse or garden centre. These protectors must be removed for the remaining months. It is recommended to cut down the Hostas which would remove the food source attractant.

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.