To Hatch, or to Fly?

This depends very much if you happen to be an embryo camped under a bud scale or as a pupae under the grass.

Just one defined cold, frosty spell, to date. Since when choosing one’s wardrobe early in the morning has invariably resulted in cast off garments hanging, reflecting the temperature climb through the day.

January has actually given time for the land to begin to dry a little, though desiccating winds from the East never materialised, at least the amount of precipitation has been more manageable.

Eggs of the Winter Moth require a temperature of 13.5C to hatch. They are, at the moment, where they were laid distributed around the apple or pear tree, usually within the shelter of the bud scales. Once hatched they seek food. Should the temperatures be sufficient to initiate an early bud break, then any oppurtunity to enter the unfolding bud will be taken and the unfolding minute growth will be consumed, resulting in negating the blossom buds.

As a pupae of an Apple Sawfly, a wake up call is initiated as the soil temperature rises. At this time of the year this is accelerated by sunshine – not that this has been that prevalent recently. As the days draw out and the sun becomes more powerful so these pupae are initiated into releasing their inhabitant. Until roughly ten years ago the saw fly emerged from the soil during the latter half of April, coinciding with the first apple blossoms wherein eggs are laid resulting in considerable damage to fruitlets. During recent years when Spring temperatures have been noticably warmer, earlier from late February and during March, the damage from the Apple Sawfly to the crop has been negligible – they have emerged earlier to find no flowers to deposit eggs in.

Good news, you might wonder, but is it? The above are examples of how insects react to the changing temperature pattern. They both happen to be pests to fruit growers. They are botb insects. If the rest of the insect population is being influenced in the same way especially if they happen to be pollen feeders, then their life cycle is less likely to coincide with the apple blossom period. Should a period of cold weather feature during April, then many will be weakened or not survive, especially with hungry nestlings to feed by then.

The effect of temperature ‘changes’ through the year as a whole on the actual physiology of the fruit tree is another, complex study.

It is obvious that fruit growing as I have experienced during many years is struggling. So, keep hold of your garden fruit trees!