Blackcurrant gall mite is attacking - what to do?

Sometimes in the summertime happens that the blackcurrant shrubs suddenly do not seem as healthy as they should be, also in the harvest time there are less berries as sooner years.

It can be caused by different pests or diseases, but it is most likely the result of black currant gall mite action.
In the Estonian environment, the black currant gall mite is mainly damaging black- and lesser red- or white currant, also very rarely gooseberry shrubs.

How do I know that it is gall mite? 

During the summer period, the damaged shrubs tends to be sickly and partially wretched. At the time of harvesting, the amount of berries is usually much smaller than in the previous harvest years. There are also some branches with old buds from the previous year.

The most convenient and secure is to determine the existence of pests in the spring (in Estonia the first half of March). Then look carefully at your shrubs - if there are two varieties of buds - one type rounded and the other with a sharp tip - the thing is, to put it mildly, dubious.

Buds where mites are in action. Photo: Ravel Reiljan

In this case, take a few round buds, look for a hard base and cut the buds with a thin piece of steel. Then use modern technology - (with naked eye you can't see nothing, because the size of the mites is only about 0,2mm) for example, a magnification glass or a mobile/camera macro.

There is no need to look for those characters very hard, because there may be a whole group, ie mite(s), eggs, larvae etc, in one bud. Moreover, the population of a single bud can be very large, reaching thousands of individuals - so if you have a handy tool with sufficient magnification, you will see them immediately (they have fun in bud and they fuss around).

Inside the bud - eating. Photo: Ravel Reiljan

What to do?
 

What if the diagnosis is confirmed?

Then you have to act - if the shrub is too tight, it has overgrown or drooping branches, then first thin your shrub to a reasonable extent, then start to pin out the round buds. Collect them and burn them immediately (not suitable for composting) with expelled branches - if you don't, the shrubs will soon be destroyed because the source of infection remains.

 

If about half of all buds remain in the shrub, the shrub can usually cope with the situation itself and begin to recover quietly next season (this activity must be repeated every year until the problem is off the agenda).

But if the bush has practically all buds inhabited, the story is more complicated - in this case, the situation should always be based on - how long have the symptoms lasted? Are there few or many shrubs damaged? Is there a risk of major financial damage

In this case, the use of a systemic poison or destruction of shrubs may be considered. You should now consult a professional.

When it is best time for pinning buds or thinning shrubs?

The most convenient time for this is actually the first half of March (in Estonia), because you can then easily make the difference of the good and bad buds, and this time is also well suited for thinning shrubs.

What more to notice?

A very important aspect - always disinfect the cutting tools before going to a new shrub and after cutting the last shrub.
Use antiseptics for this purpose (vodka is not suitable).

Why do they come to my plant?

If we are dealing with a shrub grown from good material that has been properly nursed in a nursery and then properly planted in a growing site/soil and has been properly maintained in the garden (agrotechnics), then this question is really justified.

However, if any link in this sequence is so weak that the plant cannot handle it quickly, it is not good - the stressed plant is susceptible to various malignancies and diseases, and then the serious problems are no longer far away.

So - the presence of mites in your plant is usually (in the case of mites, often the question is bad reproductive material) is a plant emergency call for you as a caregiver - something is wrong with the plant and it needs your urgent help.

How to help?

In this article I wouldn't better deal with it because the subject is more sizable and requires a separate approach - however, some of the risk factors I have noticed are: untreated (too tight, aged) shrubs, autumn leaf and placing apples under the shrub, ash throwing under the shrub and excess soil acidity. If you are attentive to these things, there is already a high probability that your shrubs will be healthier and stronger.

Source: Urbandendro
http://ravelreiljan.blogspot.com/