Steward – March 2020

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Nicotine doesn’t affect my seeds, does it?

Take a load off

Master Gardener Coordinator’s Corner

Nicotine doesn’t affect my seeds, does it?

By Michael O’Brien, Advanced Extension Master Gardener

Now that March is here the ideas are flowing, spring is coming.  Thoughts of what to grow this year are beginning to pop-up in our mind.  Starting plants from seed is fun and economical too. It’s also a fantastic way to teach children.

So the question is, does nicotine really have an effect on seeds?  Yes! If a person was to smoke a cigarette there would be trace amounts of nicotine on their fingers.  And it’s the same for chewing tobacco too. Surprisingly enough, if that same person was to touch seeds, there is a high probability that nicotine would get on the seed.  

In a study done by researchers, they studied the effects of nicotine on the germination of radish, kale, lettuce, wheat, rice, barley and rye seeds.  The results showed the seeds had a very noticeable delay in the rate of germination in all cases. Scientists found that it caused a reduction in the levels of certain enzymes known to be significant in the germination of these seeds.

In the 1950’s researchers started testing the relationship between nicotine, seeds and plants.  They found nicotine can be very affective in killing insects. It was a great discovery, it protected the plant and with the plants being protected it would increase yield production as well.   The goal was to assist farmers so their seeds purchased would have a higher success rate in seed germination. The challenge they were working with was, how to limit or stop insects and funguses from destroying the seed.  The answer was to coat corn seeds as well as other seeds used for mass production with a powder that had nicotine in it. Though the years of using this type product it has now created farmland that is saturated with nicotine.

There was another product created that is still in use today as an insecticidal spray.  This spray is made from derivatives of nicotine. This product is classified as a neonicotinoid.  This spray is designed to over stimulate the nervous system of insects, causing the insect to experience paralysis and death.  Today, there are currently around three hundred different products in this classification. The specific active ingredients include acetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, and thiamethoxam. 

Research has shown the problem with these insecticidal sprays is that they can’t discern between harmful insects and beneficial insects.  Many beneficial insects that are seriously being harmed are bees, ladybugs and Monarch butterflies to name a few. What is so concerning about neonicotinoids is the effects it is having on wildlife that pollinate our crops, its ability to infiltrate groundwater and its cumulative and largely irreversible effects on invertebrates. As practicing gardeners and stewards to the environment, whenever possible we should avoid all products that contain neonicotinoid, to be safe. Gardening pesticide-free is ideal.

Pawpaw leaf-rolling caterpillar (Lepidoptera), Ompalocera munroei, and webbing in a pawpaw leaf (Asimina triloba). Photo from Missouri Botanical Garden

Take a load off

By Cheryl Gross, Advanced Extension Master Gardener

It is March!  April is around the corner.  With each day of warming gardeners develop a real itch to get into the garden and begin spring clean-up and preparing the soil.  Not so fast, buster. Remember all of the articles and Facebook posts last fall about leaving the leaves to protect insects? Rushing clean-up defeats all of that good thoughtful fall effort.

Some of our wonderful, beautiful, valuable insects overwinter in leaf litter.  The smart gardener knows now to leave the leaf litter where it is to house and protect the eggs, larval forms, and even some adult critters.  Therefore if you have taken the “smart” fall practice, rushing your spring clean-up will ruin all of your good works.

What we know now is that many insects need about 50 degree daytime temperatures to get moving.  This means that you should allow your gardens a minimum of 5 days of nice warm 50 degree weather before you begin to disturb the leaf litter.  

Some may argue, but what about the spring bulbs and early bloomers?  Don’t they need to be uncovered to grow? Not likely. Look at the woodland floor for evidence.  Trillium, Dutchmen’s Breeches, Trout Lily, Celandine Poppy, and more all manage to push though leaf litter with no help from a gardener.  If they can do it, crocus, daffodils, and tulips can do it too. Additionally, leaf litter helps warm the soil slowly without the sun directly beaming on the soil surface.

As for prepping beds for planting, the soil needs to reach at least 55 degrees for successful germination and working wet soil has very bad outcomes ,  including disruption of soil biology and compacting the dirt.

Best gardening practices in northwest lower Michigan in April?  Take a hike, visit a botanic garden, start seeds indoors, and read a good gardening book.  Resist the urge to garden too soon. The short gardening season will still arrive and you will be plenty busy on your knees then.   Until the bugs are out and about from the leaf litter, go ahead and take a load off.

 

Coordinator’s Corner: Spring Cleanup That Protects Pollinators

By Nate Walton, MSU Extension Consumer Horticulture Instructor and MG Coordinator

This article is a follow-up to my article about fall cleanup to protect pollinators which you can read in the September 2019 edition of The Real Dirt. 

A pollinator is any animal that moves pollen from one flower of a plant to another flower of the same plant species. In Michigan, our most important pollinators of most native plant species are wild bees. For our insect-pollinated agricultural crops, wild bees contribute to pollination, but most require that large numbers of European honey bees (Apis mellifera) be placed nearby in portable hives.

Honey bee hives placed in a blueberry field for pollination of the crop (N.Walton, MSU Extension). Honey bees are an irreplaceable component of modern agriculture, but you don’t have to worry about them during your spring garden cleanup

Wild bees do not spend the winter in hives, they overwinter in protected locations in a state of hibernation. There are at least 465 species of wild bees living in Michigan and scientists are only beginning

3 native wild bees enjoying the resources provided by this early spring flower (N. Walton, MSU Extension).

to understand where most of them are located in the winter and how we can use that information to protect them. Most wild bees (about 80%) construct their nests in the soil at depths from just a few inches, to as deep as 1 m. The remainder are

called cavity-nesters and they use pithy stems (e.g. elderberry, sumac), hollow stems (wild grasses), or beetle borings in dead trees. For these soil and cavity nesting bees, conservation is a little bit easier because their nest location is also their overwintering location. With some careful observation of the bees in your yard, you should be able to see where they are nesting, make note of it, and protect that area from disturbance. 

There is probably not much that you need to do differently from your normal spring cleanup routine, to protect the soil nesting bees. On the other hand, if you left ornamental grasses or herbaceous perennial stems unpruned last fall, they may now be harboring cavity nesting bees. When you cut them back this spring, try to allow the stems to remain intact by using sharp tools. Then, you can place them in an out of the way location where the bees will be able to emerge from the nests naturally.

The compost pile is probably not the best place to place plant material that may contain overwintering bees, because there is too much moisture there and the bees may die from pathogen infections. I would recommend having a designated brush pile for all of the material that may be harboring overwintering pollinators. Keep the pile light and airy to prevent moisture accumulation. The timing of your stem cleanup can be somewhat flexible but there are a few important facts to keep in mind. First, the cavity nesting bees will be happiest and healthiest if they are allowed to emerge from the stems while they are still in their natural position (i.e. attached to the crown that they grew from originally). Second, the exact timing of natural emergence depends on the species and climate in your area. And (third) if you wait too long, they will start creating new nests in the stems. Disturbing freshly created nests is much more harmful to the bees than disturbing the bees while they are still in hibernation. Fourth, sometimes the best time to prune is when you have the shears in your hand. 

Another important group of bees that I have not mentioned yet, are one of springtime’s most conspicuous pollinators: Bumble Bees. Bumble bees are social bees, which means that they have a life cycle that includes several generations of workers living together in a communal nest. However, their colonies are started from scratch each spring by solitary queen bees called foundresses. The foundress mated the previous fall and spent the winter in a sheltered location, waiting for her chance to search out a location for her new nest this spring. Scientists actually know very little about where bumble bee queens spend the winter and they would like to know more. If you are interested in helping them out, you can join the Queen Quest citizen science project (https://www.queenquest.org/about.html).

A bumble bee on weeping cherry in April 2017 (N. Walton, MSU Extension)

Anecdotal reports gathered over the years, give us some idea of where you are most likely to encounter bumble bee queens before they break hibernation. They seem to seek out loose litter, such as that you might find under a pine tree or other conifer. Some of them seem to even like burrowing down a few  inches below the soil under the turf in our lawns. They also seem to have a preference for slopes and for locations with an adjacent vertical barrier such a tree, shrub, or building. In other words, they may be in a lot of the areas where you are targeting your spring cleanup activities. It can be quite harmful to disturb hibernating queen bees before it is warm enough for them to fly and/or seek out a new shelter.

This is one of the reasons many advocates of pollinator protection during spring cleanup recommend waiting until the temperature has been consistently over 50 degrees for five days before cleaning up your leaf litter of disturbing a lot of soil in your garden (see “Take a Load Off” by Cheryl Gross in this month’s The Real Dirt). If you do come across an overwintering bumble bee queen during your spring cleanup activities, the best thing to do is to gently return her to where you found her and replace the layer of leaves or duff that had been protecting her. 

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