Why Prune a Tree, Particularly in the Winter?

High summer season can be a pain for gardeners on the bug and disease front. A number of the conditions of earlier in the season will still be hanging about unless they were appropriately dealt with and both July and August have a few of their own to tax our resourcefulness.

Tree fruit is the leading target, and the leader of the pack has to be Codling Moth (the 'g' is optional ). This is a tiring monster, and is typically only discovered when the fruit is gathered and the destructive results of the larvae are all too evident. The evidence of the Codling Moth remains in the eating, and otherwise healthy-looking fruit will be found to be anything but healthy when you take the very first bite. The chewed up interior provides distasteful and sufficient proof of the caterpillars' activities.

This is a tricky one, as the moth lays its eggs in the flowers way back in the spring. When the larva hatches it feeds on the unripe fruit and departs, typically prior to ripening, typically by way of the 'eye' of the fruit, and hence avoids detection. The fully grown caterpillars then move downwards to pupate in cracks and crevices in the bark.

One from of control is to trap the mature larvae on their method to their pupation websites. The technique is to connect bands or sleeves of corrugated cardboard around the bases of the primary branches and/or around the tops of the trunks. The concept is that the coming down larvae find these cardboard hideaways to be appealing pupating areas and sit tight. Early in September, when the down migration is well and really over, you eliminate the bands, discover the cosily ensconced Mesa Trees pupae and get rid of them appropriately. It might not conserve any fruit this year however must minimize the population next season.

Another scourge of apples which may be puzzled with Codling is Apple Sawfly. This wasp-like insect likewise lays its eggs in the blossom and the larvae likewise feed on the establishing fruit. The differences are that the sawfly larvae generally do their worst rather more quickly and the damaged fruitlets fall off before they are completely grown. The larva often leaves a noticeable scar from its early activities near the 'eye' end of the fruit and normally emerges from a hole in the side. The hole is normally marked by a yukky mess of dark brown frass. Once the fruit has actually fallen the larvae take sanctuary in the soil to pupate.

The trick here is to catch them before they can manage the escape manoeuvre. This means taking a look at the fruitlets on the tree and getting rid of and destroying any which reveal the tell-tale scars. As the scarring is not entirely common, collect any fallen fruitlets day-to-day and damage them too. Once again, this will not do much for this year's crop however should help to lower next year's Sawfly population. If you have a location of bare soil around the trees it will be an excellent concept to fork it over to expose the pupae to the birds before using the fall mulch.

Apples are not alone amongst the tree fruit in being susceptible to maggoty bugs at this time of year. Plums are vulnerable to the depredations of the appropriately called Plum Moth. This has a similar modus operandi to its apple counterparts, the larvae consuming the centre of the fruit and leaving a nasty, frassy mess behind them.

The impacted fruit usually ripen too soon and may also be spotted by shallow imprints on the surface area. Analyze the trees regularly and eliminate and destroy any dubious-looking fruit. Like Codling Moth, this one tends to pupate in bark crevices, so the corrugated bands may assist if you do not rely on the birds to do the job.

These fruit bashers are quite hard clients and we are not likely to be able to get rid of any of them by natural means, however we can definitely reduce the damage and ensure we get a good crop. There are events when we just have to accept some losses in the natural cause.

August is mildew month.

Powdery and Downy Mildew afflict the foliage of an entire variety of plants at this time of year and, for starters, it may be great to compare them. Powdery Mildew usually reveals its existence with a white, floury coating appearing on the upper surfaces of the leaves. This is followed by more 'fur' on the lower surface areas, infecting stems and buds, and distortion of the young foliage.

Its Downy cousin typically appears initially as angular yellow spots, primarily between the veins on the upper surface area of the leaves. It is most evident on the young leaves, and can be confused with a variety of chlorosis-causing mineral deficiencies. The next phase, however, confirms the existence of the fungi. A grey/white fur appears on the underside of the leaves and, if the infection is untreated, the entire plant will start to look rather sorry for itself.

Between them, these two attack almost any garden plant from apples and roses to brassicae and cucurbits. They are unpredictable monsters and can take place basically anywhere at this time of year, however it appears that some environmental conditions favour their spread. When the soil is dry and air conditions are humid, as a basic rule they seem to grow finest. There is very little we can do about air humidity but we can ensure that the soil surface does moist out. To fight the mildews' preferred conditions as much as possible we should mulch mightily to maintain soil wetness without excessive water use, never utilize overhead watering, and space plants such as to allow a good air blood circulation.

The other necessary anti-mildew action is the removal of infected foliage as soon as the very first indications of the fungi are spotted. There you go: watchfulness and quick response again.