Milkweed Menagerie

By now we all know Monarch butterflies flock to Milkweed. And if you have been caring for Milkweeds planted for the Monarchs you have noticed that a lot of other insects find these plants appealing as well.

Two insects I found crawling around the plants in early July are the Oleander Aphid and the Milkweed Leaf Beetle.

Large Milkweed Leaf Beetle Larva and small orange Oleander Aphids adorn Swamp Milkweed in early July.

 

The Oleander Aphid occurs in great numbers on the stems of various milkweed species. These aphids, like many other aphid species come with their own set of concerns.  While the Oleander aphid has been documented transmitting viruses, these are primarily found in subtropical regions, here in PA the most cause for concern with an oleander aphid infestation on milkweeds is the unsightly residue they leave. These aphids, like many others, secrete honeydew, the waste product produced from their piercing sucking feeding methods.   On the sticky, sugary honeydew, black sooty mold forms. This can make the milkweeds look terrible but will not kill the plant. The feeding of the aphids may cause stunted growth, and damage at the newest, tender growth.

Oleander Aphids coat stems of Swamp Milkweed (Asclepias incarnata)

 

Though now found throughout the world, the Oleander Aphid is originally native to the Mediterranean region where its namesake is found growing wild. While it is difficult to prevent Oleander aphids from seeking out your milkweeds, you can implement some cultural practices that may make the milkweed a less than desirable habitat for these black-legged, orange-bodied insects:

Cultural Controls:

• Reduce irrigation, pruning and feeding to limit growth of the tender new shoots preferred by these pests.

Mechanical Controls

• Before the infestation gets to large or while it is limited to a small portion of the planting, prune out infested areas.
• A strong stream of water from a garden hose will dislodge many aphids, and according to the University of California IPM most dislodged aphids will not be able to re-infest the plant. As an added bonus you may have washed off some of the honeydew.

Biological Controls

• There are parasitic wasps that attack aphid populations. You may notice “aphid mummies” among the living aphids on the plants. These papery brown swollen aphids are evidence of a healthy beneficial insect population.
• Syrphid Fly larvae
• Green and Brown Lacewing larvae
• Ladybug Larvae

 

Chemical Controls

• Insecticidal soaps and horticultural oils provide the best chance for control while protecting the pollinators and beneficial insects.

Adult Milkweed Leaf Beetle on Butterfly Weed (Asclepias tuberosa)

 

While you are out examining your milkweeds, especially the Swamp Milkweed, Asclepias incarnata, you may notice a black and reddish insect slowly ambling around among the aphids. Nope – this is not the larva of the ladybug or even a ladybug herself. Though this is not a beneficial insect, this is a native insect and there is no need for control. If they are eating your milkweeds and you worry there are not enough for the monarchs – plant more milkweed!!

The larva of the Milkweed Leaf Beetle may be mistaken for ladybug larva however this larva of this leaf chewing insect is more rotund and shiny than that of a ladybug.

Like most of our native insect/plant relationships this insect has figured out how to get past those milkweed toxins that many other insects and animals find unpalatable. Before they start chewing on the leaves, these insects, both the adult and the larva will chew a notch into the vein of a leaf to drain out much of the toxin before they start consuming their foliar meal.

Controls for the Milkweed Leaf Beetle are typically not necessary. On rare occasion they may strip the leaves of the plant, and in that case you know you need more milkweed! But should you or your client decide control is necessary here are some suggestions:

Mechanical Controls

• The larva and adults are big and slow and easy to catch. If the population is small enough consider hand-picking them off (or leaving them for other insects, birds and mammals to feed on.)

Chemical Controls:

• The same insecticidal soaps and horticultural oils used to control the Oleander aphids will also control these leaf beetles

Just as there are multiple species of milkweeds (11 species native to PA alone!) there are numerous insects using this plant for food. Before you reach for the controls, examine the plant, monitor the plant, make sure you know the harmless insects from the harmful insects and take great care to explore the existing control measures provided by beneficial insects before taking any further actions.

Subtle and Bold

When thinking about protecting pollinators – don’t just think showy!

Today I ventured out in the Penn State Extension – Bucks County Demonstration Gardens. These gardens are thoughtfully designed and lovingly cared for by the Bucks County Master Gardeners. They are designed and cared for with education in mind. This means we use the gardens as a place to learn and a place to experiment. This also means these gardens, and similar gardens at extension offices across the state are there for you to explore, examine and learn from. Stop in for a visit!

As I wandered today I noticed Monarda “Raspberry Wine” in full bloom and abuzz with numerous pollinator species. Of course the magenta flowers of this native perennial are attractive to the pollinators. (Attractive to Japanese Beetles too, as you will see in one photo!) and because they are so vibrant you may automatically assume they are covered in pollinators and keep the chemical applications to a minimum in its vicinity. But I encourage you to take a closer look at the residents of the landscape with more subtle flowers. For instance, the Pycnathemum muticum, Mountain Mint,  blooming in the Native Plant Demonstration garden was absolutely loaded with pollinators as well. You may take one look at this perennial native and assume that not much would be visiting it and a chemical application would do no harm, but you may be mistaken as you can see in the photos below.

So before you head out for a chemical application, be sure to take a thorough wander through the gardens. Do not be distracted by the bold stand-outs and forget to take a look at the more understated blooms as well – they could have just as many, or more, beneficial insects as their audacious neighbors.

The Bagworms are Crawling!

When Catalpas bloom it is time to start looking for the crawling stages of bagworms.

 

This is a fascinating time of year, and a fascinating year in general if your are an Extension Educator. The weird spring weather (remembers those 80+ degree March days, and that the sun never shone in April?) has resulted in a bumper crop of fungal diseases and strange timing for other pests.

Phenology is the use of plant life-cycle stages as indicators for various life cycle stages of pests and disease in order to apply the most effective and efficient controls. For example, when the catalpa is blooming, bagworms are crawling and extremely susceptible to chemical controls. And when the black locusts are in full bloom – this is the time the emerald ash borers are emerging from their in-trunk shelters and exposed and can be controlled.

The catalpas were in full bloom this week, before the gusty thunderstorms knocked the flowers off the trees today and so I knew to start looking for the tiny stages of bagworm. Now most folks are familiar with bagworms in their full-size stage. They are quite frequently found on conifers, seeming to prefer arborvitaes nearly as much as deer do. However, they have a host plant list as long as my arm and can even be found stuck to any number of inanimate objects such as dumpsters and garage siding.

I was called out to a site this week to take a look at some sickly honeylocust. Now there were a few different types of pests on these well-established roadside trees, and the bagworms weren’t causing the damage I was looking at (Check out this Penn State Fact Sheet on Honeylocust Plant Bug for more information). But upon closer inspection I noticed the tiny larval stages of bagworm creeping around what leaves were left on these trees. These tiny creatures look like the debris on any tree and blend right in (nature is amazing!) easily missed.

Tiny instar of bagworm larva on honeylocust leaf.

Are you wondering just how small that is?

Bagworm larva and a dime.

If you watch these tiny insects closely you will see a small dark brown to black larva (caterpillar) emerge and feed on the leaves as they move around with the tiny beginnings of their new homes on their back.

Consistent monitoring is key for catching small problems before they turn into large ones. Knowing what else is happening in nature when the insects are small and hard to see will help you manage your pest populations.

The Most Wonderful Time of the Year

Usually a phrase used around a certain winter holiday – for me this is the most wonderful time of the year. Happy First Day of Autumn!

Asters are a welcome continuation of color into the fall months.

Today just happens to be an extra beautiful day in addition to the first day of fall. The sun is bright, there is a cool breeze and the temperature is hovering at comfortable.

Today I spent some time under my very favorite type of tree – the Katsura Tree (Cercidiphyllum japonicum). The tree here at the office is perfectly shaped thanks to our Master Gardener volunteers and currently sports a fragrance some describe as cotton candy, baking sugar cookies, vanilla pudding, or brown sugar. It is a sweet perfume that ignites the autumn air and for me, this is the smell of fall.

These green leaves do not give away their scented secret just by looking. You have to visit a Katsura in person, right as the colors are changing to earn the joy of this sweet scent.

It is not flowers that make this scent but the turning of the foliage, the chemical process by which these dainty heart-shaped leaves transition from true green to egg-yolk yellow, creates as a byproduct something I wish they would bottle and sell or make into candles.

Gypsy Moths

Gypsy Moth Caterpillar on Fothergilla gardenii – a face only a mother could love. This gypsy moth is responsible for large missing sections in the Fothergilla leaves, those smaller holes and discoloration are from 4-lined plant bugs.

Gypsy Moths

Since I learned a lot more about moths by participating in National Moth Week events in years past I have become obsessed. I sit out at my porch light each night trying to identify the moths resting on the screen door (and the spiders there to eat them) and marveling at the diversity and beauty of this night time wildlife.

Sour Mulch

Mulch Pile

Over the past few days we have received a number of phone calls from Landscapers and Homeowners alike all with the same problem: within 24 hours of applying mulch plants in the area all have dead leaves and appear burned:

Tender new growth of Japanese Painted Fern (Athyrium niponicum) damaged after ‘sour mulch’ application.

Since we were getting multiple calls about this, I headed out to a site to take a look and talk to one of the landscapers experiencing the problem.

A logical conclusion to draw when you see this happening in a landscape in your care is that there is something in the mulch causing this to happen, especially when you have been mulching for years and have never had this happen before. Many of the people who called were interested in having their mulch tested for herbicide residue or some other chemical component that would be the cause of this damage. But if you are noticing bleached, scorched or yellow leaves,  chances are the problem is Sour Mulch AKA Toxic Mulch or Wood Alcohol Syndrome.

A Reason for a Messy Fall Clean Up

Or the reason for a delayed spring clean up.

Often we are asked to clean up the messy fall debris in time for winter snow and to make sure spring blooms and new shoots have plenty of unobstructed room to grow. Today’s first day of spring snow gives us evidence as to why we should reconsider that trend.

A Robin, puffed up to keep warm, finds protection in the butterfly garden in Bucks County Extension Display Garden

Migrating birds taken by surprise at this snow and resident birds tired of fending off winter blasts and ducking clumps of snow falling from branches can and will take refuge in standing branches and stems not taken down in a fall clean up.

A Day in the Life…Microscope at Work

Samples ready to be investigated

My job is to answer questions and teach research based facts to professionals in the green industry (landscapers, horticulturists, nursery and greenhouse growers) and in commercial vegetable, small fruit and tree fruit production. I also handle questions from residents and home gardeners when the Bucks County Horticulture Hotline is on a well-deserved winter hiatus.

The variety of questions is amazing and the way in which they come in is nearly equally varied. I get questions via email and phone, some folks walk into our office looking for answers while others tape their questions to the door or slip it right underneath early in the morning or later in the evening.

Recently, someone dropped off samples of a tiny brown moth and its larva they found in their garage. Of course they wanted to know what the insect was, and more importantly, perhaps, how to get rid of it.

Those Darn Deer

A tough winter in this region is as tough on the region’s wildlife as it is our plants.  Nearly everyone has dealt with deer in the landscape at one time or another. A question I hear frequently is

What can I plant that the deer won’t eat?

Good question! And the short answer is: Nothing!  What the deer will eat depends on a large amount of variables. Everything from weather; availability of desirable food; deer gender, age, health; deer population in the area; and existing travel paths influence whether or not your plants will get eaten.

Some plants seem to be a selection of last resort and are less frequently browsed. One of my go-to answers for deer-resistant plants to try are Ferns. Any type of fern. Ferns seem to make it through season after season unharmed…

… and here’s a picture I took from my office window of a young deer eating ferns out of the Demonstration Gardens in the front of our building. So much for ferns… those darn deer.

Deer Eating Ferns from the Bucks County Extension Demonstration Gardens

Photos of the Backs of People’s Heads

Winter is the time for professional development. This works two ways – I present professional development opportunities for tree fruit and vegetable growers and green industry professionals through a variety of regional conferences and webinars and I get to learn some new things as well.

In the past few weeks I have found myself hosting our Green Industry Winter Webinar Series (there’s still time to register!), attending the Mid-Atlantic Fruit and Vegetable Convention where I assisted with the A/V and attended a few sessions on Tree Fruit Production and using Social Media to market your farm and product. I attended the Pennsylvania Sustainable Agriculture Conference and co-hosted the Southeastern Regional Tree Fruit Growers Conference.

I want to share pictures of these programs. The programs are fascinating and there is so much to learn. But as I go through the photos, I see they are mostly of the backs of people’s heads: