Mystery of the missing apples

At a function I attended over this past weekend the conversation turned to gardening. A friend mentioned his apple trees were being raided by an unknown animal. This animal was very stealthy, so stealthy in fact, that it left virtually no trace of ever being there.

The thief left no footprint despite the fact that apples were missing from all parts of the tree. Every branch had missing apples and none of the branches had any damage whatsoever. Apples taken from high up the tree implied the animal was either quite tall or was a good climber.

Since this is early in the growing season, his apples are still small and still in the developmental stage, about the size of a cherry. Maybe the suspect was a bird?

Our little group spent some time discussing all of the other factors surrounding the case: when did it happen? what other plants were near by? where there any apples on the ground? was grass growing under the tree? and so on.

I’ve come across this kind of mystery with apples before and it always takes place this time of year. As the tiny apple fruits grow, a natural phenomenon happens during the course of their development. The an apple tree cannot bring all of its young apples into full-sized mature fruit. There are not enough leaves to generate the amount of photosynthesis required to grow out all of that fruit. And even if there were, the shear weight of all of those apples would break off the branches. So the tree cuts off the flow of nutrients to a large number of young apples causing them to fall off. This phenomenon is sometimes called the “June drop”.

To make excess fruit fall off, apple trees form an abscission layer that stops nutrient flow to the developing fruit.

It was the June drop that was the cause of my friend’s missing apples. The apples fell very quickly over a short period of time which would explain the lack of damage to the tree. Once they were on the ground, mice and other small animals took advantage of the bounty and ate them or carried them way.

Bob

 

 

Milkweeds can become a nuisance

In this day and age pretty much everyone knows about the relationship between monarch butterflies and milkweed plants. It wasn’t always that way.

Before modern chemical weed killers, farmers had limited ways of dealing with weeds. Depending on the weather conditions, a farmer might have to go over a field two or three times with a horse drawn cultivator. Later, cultivators were mounted on tractors but the process stayed the same. An efficient farmer could do a pretty job of controlling most of the annual weeds, perennial weeds were harder especially if they became established in a field. The only thing to do was to send the family out to the fields with hoes to try to keep the weeds at a minimum.

Milkweeds were one of those perennial weeds that farmers were constantly battling. When the first herbicides were developed, farmers no longer had to spend so much time and energy constantly going over their fields. Perennial weeds like milkweed still were a problem however and farmers hated them. I remember when I was young seeing a beautiful field of some sort of crop — I don’t remember what crop it was — that was completely free of weeds except for a colony of milkweeds that you could see from over a hundred yards away.

Nowadays modern herbicides are very efficient at controlling all types of weeds so we never see milkweeds in farm fields anymore. They’re limited to fence rows, ditches and other out of the way places. The number of milkweeds for monarch butterflies to lay their eggs on and for their caterpillars to eat has been drastically reduced. Now, farming organizations that used to join in the battle against milkweeds now pass out seeds and encourage people to re-establish them.

Milkweeds still have the potential to get out of control and become a nuisance. Once they become establish they will spread by way of underground roots. Those roots are very tough and strong and are able to push themselves into surrounding areas and compete with other plants. In one spot in my yard, I started out with a single milkweed plant next to my garage a few years ago. That has now turned into a colony of plants that is over 40 feet long. One of these days I’ll have to do something with them before they really get out of hand.

The nearest milkweed stalk is over three feet away from this shoot pushing up through the concrete expansion joint.
The nearest milkweed stalk is over three feet away from this shoot pushing up through the concrete expansion joint.

Another patch is beginning to encroach into the vegetable garden. They’re pushing their way up through seams in the plastic mulch I have laid out.

I don’t mind my milkweeds being a bit unruly, it’s fun , at least for now, to see those plants thrive in the yard. It reminds me that it won’t be long before the monarchs are back.

Bob

 

 

Finding a sphinx moth pupa

Butterflies and moths overwinter in different forms depending on the species. For example, the famous Monarch overwinters as an adult, swallowtails in the chrysalis stage. Other species of moths or butteries spend the winter as as eggs or as pupae.

Earlier this week I was filling up a plant container with growing mix that I had saved from last fall. The mix was stored in a few open trash cans inside the barn. Using an antique coal shovel, I was able to make good  filling transferring the potting soil to the planters. I noticed in one trash can, lying there in the soil mix, was a brown, leathery looking cigar-shaped thing. Looking closer I could see it was a large insect pupa, that of a sphinx moth.

A sphinx moth is the adult stage of the tomato horn worm, those big, ugly, destructive caterpillars we often see chomping away on our tomato plants during the summer.

Sphinx moths are one of those species that overwinter as pupae. As autumn approaches, the huge hornworm caterpillars leave the plant and burrow into the soil to morph into a pupa. Although hornworms are abundant, finding a pupa is relatively rare. That’s because they burrow so deeply. Most rotary tillers only till to the depth of six or seven inches or so. A gardener with a spade may work the soil as deep as eight inches. The hornworm tunnel down to at least a foot, well under the disturbed topsoil layer.

A sphinx moth pupa is not uncommon but is rarely seen.

 

The caterpillar that formed the pupa that I found came from one of two places, it either traveled from the garden and crawled up the side of the trash can into the mix, which is highly unlikely. Or, I missed it when I was emptying the deep planters last fall, which is probably what happened. One of the planters did have a couple of tomato plants in it, that would explain why the hornworm was there in the first place.

The sphinx moth pupa has a kind of “jug handle” structure that contains the moth’s long tongue.

We have a love-hate relationship with these insects. During their caterpillar stage they can be quite destructive, defoliating entire plants sometimes.¬† As an adult however, they are fascinating. They don’t have much color but they are quite large and at first glance are often mistaken for a humming bird. They act like a hummingbird too as they hover over flower blossoms gathering nectar.

So, I have a decision to make: should I squash the pupa so it won’t develop into a garden pest later in the season, or let it go to emerge as an interesting visitor to the flower garden. What would you do? Let us know in the comment section below.

Bob