Shred Those Leaves

It's fall, and once again I have designed and built my very own leaf shredder. This one is the Mark Three model. The Mark One and the Mark Two were failures . . . well, not failures, just a little too risky to operate. Using them could have got me featured in one of those TV shows on extreme sports. This model is much safer.

I first began designing and building leaf shredders about five years ago. The Mark One used an old electric lawn mower that I tried to modify by cutting a hole in the top and mounting it on a wheelbarrow.

The idea was that I'd stuff the leaves through the hole where they'd be finely chopped by the whirling blades below before falling into the barrow for composting. It did work, but only one handful at a time, and after seeing what it did to the wheelbarrow when the mounting came loose I quickly remembered that I had only two hands -- each containing five, very useful, fingers. I junked it; there are some things you don't want to discover when turning compost.

The Mark Two was much more promising; it almost resembled a store-bought shredder. I built it with parts from an old washing machine. I was able to use the drum as a hopper and the motor to drive the shredding rod. With a few modifications to speed up the rotation, the mark two looked as though it might do the trick, but I never did get the chance to toss any leaves into it. As soon as I plugged it in the thing took off down the yard like a Star Wars pill bug battle droid.

What surprised me was the illusion I'd built artificial intelligence into the Mark Two. The way it zeroed in on Mrs. Fellini's cat was astonishing. I didn't even know the cat was skulking around behind the spirea. When the cat leapt the fence in a single bound the shredder immediately changed direction, rolled up its extension cord and unplugged itself.

Fortunately, the length of the cord limited its range otherwise I would have had some explaining to do to Mrs. Fellini. I dismantled it right away before it figured out how to plug itself back in. The last thing I need is a barren wasteland and a leaf shredder thinking it's smarter than I am.

Now I have the Mark Three. I made this one with a large plastic barrel that I'd planned to use for storing rainwater and the motor from a hot tub pump that I decided might be a tad powerful for the pond.

This one is a much simpler design than the Marks One and Two, and I'm sure it will be a winner. All I’ve done is attach the motor to the bottom of the barrel and added legs.

At last I'm ready to shred, and I can't wait. All I have to do now is find enough leaves to begin performance trials. Did I mention it resembles a huge food processor?

It's funny how actions that would normally be considered uneventful can be seriously misunderstood when performed out of sequence. As a gardener/inventor it seemed perfectly logical to me:

             (a). Leaves needed to test out new leaf shredder.

             (b). Collect leaves.

             (c). Leaves have not begun falling yet.

             (d). Leaves grow on trees.

             (e). Collect leaves.

I shouldn't have climbed the tree. All right, it may have appeared a little unusual, but I don't think there was any need for the neighbours to call the emergency response team. It was so embarrassing, and I had a fair bit of explaining to do.

At first I told them I was trying to rescue a cat, but they heard Mrs. Fellini snort when I said it, and when I dropped the bag of leaves they had me. They were all for taking me downtown (Mrs Fellini was yelling encouragement), but I was able to convince them to let me demonstrate my leaf shredder and prove that I wasn't nuts.

Lucky for me it worked perfectly first time. It might have been better if I'd let the leaves dry out a bit first, but it did a terrific job. I flicked on the switch and dumped in the bagful of maple leaves; it pureed the lot in two seconds flat. The emergency guys were so impressed they went and used the ladder truck to collect more leaves.

They all wanted to try my new shredder, and then they had to see what it would do to tomatoes -- cleared out the veggie garden. They were having so much fun I couldn't get rid of them. A couple of them want the plans so that they can build their own. One is into wine making and the other is crazy about pesto.

Funny, in no time at all I went from a code twenty-three to a harmless eccentric to a brilliant inventor. I may have to patent the mark three.

Juggling the juglone

Don’t do it! It’s the worst place to grow plants. The soil is toxic and they’ll all die. If you have ever read or heard stories about walnut trees, especially black walnut which is common around here, that’s the gist of it. But is it true? This popular belief has been widely reported and quoted over the years, often from reliable sources.Consequently, gardeners abhorred the thought of a walnut tree growing anywhere near their gardens. Because the black walnut is prized and much sought after for its beautiful wood, there’re many who would say the trees are worth more dead than alive.

The theory is walnut trees produce a chemical that inhibits the growth of other plants — the term used is allelopathy. The chemical is juglone and is believed to be exuded by the roots of the tree making the soil toxic to many plants. Other parts of the tree, including the leaves, are also said to contain juglone and it’s long been the recommendation that wood chips from a walnut tree should not be used as mulch and the leaves should not be composted.

However, it’s since been revealed that juglone is not initially present in the living tissue of the tree, but a non-toxic precursor called hydrojuglone is and it’s only converted to juglone when in the soil. I’ve composted my share of leaves from black walnut and never had an issue using the compost in my garden.

Supposedly, juglone doesn’t affect all plants. There are long lists available of those that can be grown beneath walnut trees and others that can’t. Tomatoes, it seems, can’t be grown beneath the tree, but onions can. The problem with these surprisingly long lists is they’re apparently based mainly on observation — what’s been seen to be growing well or not, but not necessarily taking into account other factors that can affect growth.

There have been few if any scientific studies that give solid evidence supporting all these plant recommendations and the same goes for the belief that growing anything beneath walnut trees is an actual problem.

The question is, where did this belief arise? We are fortunate in that someone has done the work to find out. Linda Chalker Scott, Associate Professor and Extension Horticulturist at Washington State University has only recently completed a review of all possible material related to the issue and published a fact sheet on it.

Chalker-Scott reveals that back in the 1920s, despite farmers growing crops successfully near walnut trees, the belief took hold. By 1948, the United States Department of Agriculture felt the need to issue a press release assuring the public that there was no need for concern and that the trees were harmless to other crops, but still the belief persisted. Then, in 1951, experimental field testing began and guess what — little to no adverse effects were evident.

Some laboratory testing was done using juglone directly on seeds and seedlings and there appeared to be negative effects, yet the results were inconsistent. As with any laboratory testing, it doesn’t necessarily relate to what occurs in nature. Chalker-Scott concludes that all the scientific evidence for black walnut allelopathy can be traced to two publications, one of which has been withdrawn and another that is non-existent.

So, what is going on under black walnut trees? Ignoring the myth, the answer is probably what goes on under all large trees. The roots of most trees mainly occupy the top couple of feet of the soil and spread far beyond the dripline. Light rain never reaches the ground beneath the canopy and consequently, the tree grabs all the moisture from the soil along with the nutrients. It’s always difficult to grow much under any large tree, although many gardeners have been successful.

As for tomatoes, it’s the one plant that’s said to be a good indicator of the allelopathic effect. They often fail to grow when planted beneath a black walnut tree, but then why would anyone try to grow tomatoes there? It’s about the worst place. Tomatoes need lots of water — none there. They also need good, rich soil — hardly likely. And what tomatoes really need is plenty of sunshine.

Good luck with that in the shade of any tree. Don’t do it.

Read the original work of Linda Chalker-Scott here.