June 28, 2012
Pile of earthworms. Urbanext.illinois.edu
The soils supporting our home lawns, vegetable and perennial gardens are improved by the presence and activity of earthworms. They are considered beneficial in the plant world. Earthworms move through the layers of soil creating tunnels for water and oxygen to reach the plant roots and channels for root growth. Their movement increases drainage and reduces compaction. Often called “nature’s rototillers”, earthworms feed on organic matter, bacteria, fungi and small soil particles in varying depths depositing their castings, or feces, in other horizons effectively turning the soil over. Castings are rich in nitrogen and nutrients easily absorbed by plants. Their feeding aids decomposition of organic matter, aerates soil, creates good soil structure and develops humus. The Rothamsted Experimental Station in England has done research finding as many as 250,000 earthworms per acre. That is a lot of subterranean work happening! Charles Darwin was one of the first scientists to recognize the benefits of earthworms. His last book written in 1882 is on the worm biology and behavior. His discoveries of earthworms are still being seen today.
Often after a rain, earthworms come to the soil surface then re-enter the ground head first. Some scientist think the worms come to surface for air if the ground is saturated. Others believe chemicals in the rain are inhospitable by changing pH and chemical amounts from acid rain. Still others think since the surface is moist, the worms come to the surface to mate. Earthworms are negatively affected by drying out by the sun therefore most surfacing happens at night. The action of tunneling back into the ground squeezes the worm leaving a pile of castings above ground. The casting look like tiny round balls piled up in a pyramid up to two inches depending on the size and type of the worm. Casting piles normally go unnoticed unless the turf is cut exceptionally short like that on golf course greens and tees. Home lawns should be cut to a height of at least three inches. Wet piles can stick to mowing equipment gumming up the blades and gears. The piles are easily dispersed once they dry.
Earthworms breathe through their skin. Oxygen is absorbed by mucous on the outside surface of the worm where it is transferred to the internal organs. This is called a gas exchange. The circulatory system of the earthworm contains five hearts or aortic arches. They pump fluids to blood vessels and capillary beds throughout the body circulating back to the hearts. The earthworm’s digestive system starts with its wide opening of a mouth that its throat or pharynx protrudes out of grabbing organic matter, soil particles and all that they contain. This food is swallowed down to a storage area called a crop. The food then moves to the gizzard where it is ground up by strong muscles and tiny stones and grit swallowed by the worm. Once the food is sufficiently ground, it moves to the intestines where digestive juices extract nutrients and some are absorbed by the worm. Excess digested food is then excreted as worm castings. It is these castings that are rich in nutrients readily available for plant roots to pick up. Earthworms don’t have eyes but are sensitive to light, vibration, touch and chemicals. They want to be in darkness and will move away from the light.
Chemicals added to lawn and garden can kill the earthworms. Preferred pH levels are neutral to 6.6. Adding lime in large doses can be too shocking of a change in their environment. Many earthworms will move to areas with better suited conditions or they may just die. Some insecticides and fungicides have lethal effects on earthworms. Researchers have also found earthworms within chemically treated soils to contain up to 20 times the toxin levels than the soil the worms inhabited. Stored toxins built up in the earthworms could then be passed up the food chain to animals using the earthworms as food.
Earthworms are classified as animal invertebrates. They are in the phylum group Annelida, meaning segmented worms. Each segment contains four tiny setae or claw like bristles used to move through the soil. Worms are hermaphroditic; each worm has both male and female parts with the male pores located on the outside of the animal. Earthworms are not self fertile. They need another worm to mate and reproduce. Each worm is fertilized in the mating process called cross-fertilization.
The most common earthworms found in Connecticut are Lumbricus terrestris, called the Night Crawler, and Lumbricus rubellus called Red Worm. Night crawlers are known to venture deep into the soil in permanent vertical burrows. The will come to the surface to feed also. Red worms prefer to live in a manure pile or area with high organic matter. Both of these earthworms originated in Europe and were introduced to North America unknowingly on plant material, ship ballast, wheels and shoes of immigrants. Native earthworm finding are very rare. It is not known whether native types were wiped out by glaciers scraping the earth or if the new earthworm invaders displaced the old. Different theories exist. What is known is that the earthworms that are present today are many, active and busy decomposing and recycling organic matter in rich new topsoil.
There are some invasive worms originating from Asia that are causing problem in some areas of North America. They are such fast consumers of organic material they are changing the layers of soil and eliminating the forest floor called ‘duff’. Some birds nest in the duff areas to raise their young. Insects and animals that also reside and feed in the fast disappearing habitat are also finding it hard to live. The effect of the exotic worms in the local habitat really is upsetting the ecological balance. Some populations that depend on the areas the worms are ruining might vanish forever. Research is presently being done but much more needs to happen. So does education of the general public. Some fishermen are using invasive worms for bait, then just dumping the leftovers on the ground. They are unknowingly spread the invaders. ATV and off-road enthusiasts also can pick up soil, worms and eggs in tire treads, then depositing them far from the initial infected site. Hopefully in the not too far future, more information and education programs will be available. Keep watching!
June 21, 2012
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Swarm of honeybees in a tree. Photo by J. Allen
I recently had the opportunity to see a swarm of honeybees in a tree. It was pretty impressive: a ball of living honeybees about a foot across on a branch a few feet overhead. A few bees were coming and going to and from the swarm. These bees are scouts that leave the swarm in search of a good place for a new hive. When a colony reaches the size where it needs to be divided an egg that will become a new queen is nurtured. Sometimes, even before the new queen has hatched, the old queen will leave the hive with a swarm of workers in search of a new hive location. The swarm gathers and awaits the finding of the new location. The new location may be in a hollow tree, building cavity, or other protected place. Beekeepers can collect these swarms into a manmade hive for pollination or honey production.
Once a swarm leaves the old hive and moves to its temporary location, it will stay there until a scout finds a new spot. This can take anywhere from a few hours to a week or so. For the first couple of days, the bees in the swarm are very docile and this is the best time to try collecting them. After that, they have been without food long enough to be a bit testy and are more likely to become agitated and sting.
If you do see a swarm of bees, you should do one of two things. One is just leave them alone. Honeybees are important pollinators and their population is decreasing significantly due to several problems in many areas so it is important not to become alarmed and kill them. If you would like the swarm removed, you can contact a bee specialist who will be glad to come and collect them. Contact information for the Connecticut Beekeeper’s Association is available at their website. More information on honeybees can be found at the Connecticut Agricultural Experiment Station website and at the UConn IPM fact sheet on bees and wasps. A great general reference on honeybees can be found at the National Geographic website.
June 13, 2012
The ideal “monoculture” lawn, sparkling with dew. Photo: J. McInnis
Lawns are an American obsession, and the most common form of garden activity in the U.S. Even yards with no trees, shrubs or flowers almost without exception have some form of lawn. And they are big business:
+ As of 2004, the annual value of the U.S. turf grass industry was $35 billion.
+ Total acres of turf in the U.S. is estimated to be 46.5 million acres.
+ Over 25 million acres of lawn are tended in the US equals a land mass greater than that of Pennsylvania, Delaware and Rhode Island combined.
+ As a seed crop in the U.S., turfgrass ranks # 2.
+ Nationally, homeowners spend $6.4 billion per year on lawn care.
(Source: The Lawn Institute)
As is evident from the numbers above, the turf grass industry has done a superb job of capitalizing on homeowners’ quest for that perfect expanse of lawn. It has also been instrumental in shifting fashion to a high-maintenance, intensively managed landscape.
Dutch White Clover Photo: J. McInnis
This wasn’t always so. Before WWII, Dutch White Clover (Trifolium repens) was a staple component of lawn seed mixes. As a member of the legume family, clover possesses that clan’s unique ability to fix atmospheric nitrogen to the benefit of the surrounding turf. At the urging of the companies who produced chemical fertilizers and other lawn-care products, tastes began to trend toward the more uniform look of a grass-only monoculture that we see today.
DWC is now generally regarded as a weed, and most literature available discusses its eradication. Maintenance of a monoculture lawn, with heavy applications of nitrogen and broadleaf-weed herbicides, is incompatible with the cultivation of clover. The lawn-obsessed may be disappointed that with a clover-mix lawn there is less to do!
Clover In Lawns
Clover performs best in a pH range that is compatible with the cultivation of turf grasses (6.2-6.8), but withstands New England’s acidic soil conditions very well. Tolerant of diseases and insect pests, it withstands foot traffic and mowing. The relatively weak stolons of clover combine with the roots of turf grass in a symbiotic relationship that stabilizes soil and prevent erosion in poorer soils. Clover will grow in shade and may dominate where lawn grasses struggle. Once established, it is fairly drought resistant. It’s tough.
White clover is classified into three growing types: low, intermediate and large. ‘Wild White’ or ‘Dutch White’ are best for lawns, with their ability to tolerate foot traffic and mowing. (The taller varieties are used in agriculture as cover crops, living mulch and forage.)
Benefits of Clover
For those who prefer the easier care of a clover-turfgrass mix lawn, there are benefits in addition to nitrogen fixing. Clover is an excellent forage for pollinators, providing both pollen and nectar to bees. Fruit growers report increased production in crops grown in proximity to or with a groundcover of clover. (In agriculture, the taller types of clover are used.)
Environmental and cultural advantages aside, the decision to include white clover in a lawn is a matter of individual taste. The bands of creamy-white blossoms, buzzing with the activity of bees, that appear in spring are a welcome sight to some gardeners, who may even go one step further and introduce bugleweed (Ajuga reptans), adding a dash of blue to the mix. For those who wish for a lawn maintenance regime that consists of nothing more than mowing, white clover is definitely the way to go.
June 4, 2012
I should have been finishing up planting the last quarter of the vegetable garden but instead I was trying to find homes for a bleeding heart and some corydalis that I purchased at last Saturday’s Charlton Garden Club plant sale (www.charltongardenclub.net). Local garden club plant sales are a great way to pick up both common as well as a few unusual plant species while supporting a local community service organization. Being a member of the Charlton Garden Club, I can say with certainty that we use the funds for plantings on the Common and around town, donate fresh flowers and books to the library, and hold community events, like the flower show on Olde Home Day. Members had painstakingly dug plants from their garden to donate to the plant sale and we were rewarded with a seemingly relentless rain that left us all pretty wet and chilly by the end of the day.
At any rate, as I was looking for a spot to plant my new acquisitions in the woodland walk garden, I noticed large, swollen growths on the leaves of several deciduous azaleas. Right away it was apparent that they were azalea galls but I had not noticed them on the azaleas on this side of the yard before. The odd, irregularly shaped galls come in pretty shades of pastel green and pink and cream. According to the literature, they turn brown as they mature and will eventually fall to the groudn. They are cause by a fungus, Exobasidium vaccinii. It was also mentioned that this fungal disease can infect blueberries, andromeda and leucothoe so I will check those plants shortly.
Azalea galls are large and noticeable.
Most folks living in the Northeast will remember than last year we had a particularly rainy growing season. The severity and spread of azalea gall fungus is weather related. Usually the disease does not cause serious problems except during extended periods of wet weather which favors the development of spores, their dispersal and infection rates. Spores are spread by rain and wind.
Azalea underplanted with wood hyacinths.
Last year I did notice some galls on this shocking pink azalea that came with the property and which is underplanted with pulmonaria and wood hyacinths. I thought I had pruned out all the galls but apparently not. Usually around June any galls remaining will appear covered with a whitish coating which goes on to produce many, many spores which can be picked up by the wind and rain and spread to other plants. The fungus overwinters on the plant and then becomes visible as galls the following spring. The galls may form on leaves, flower buds, and new shoots.
Prune out these interesting looking growths before they turn brown and fall to the ground.
The least toxic way of controlling this disease is to prune off the galls and dispose of them. At the same time, improving air circulation by removing some overhanging branches and spacing plants far enough apart to allow for air flow is a good idea. However, during long periods of rainy, cool weather, even these changes do not seem to reduce disease incidence that much. Several fungicides are labeled for control as well. Call the UConn Home & Garden Education Center (877 in CT) 486-6271 for chemical control suggestions. Apparently there are some new azalea leaf gall resistant varieties that might be considered if this disease is a recurrent problem. Ask at your local garden center or nursery if they carry any of them.
In the meantime, where did I put those pruners?
Good Gardening to You!