GB2098445A

GB2098445A - Method for cultivating plum trees

Info

Publication number: GB2098445A
Application number: GB8208007A
Authority: GB
Original assignee: KUPPERS HELLMUTH
Current assignee: KUPPERS HELLMUTH
Priority date: 1981-03-19
Filing date: 1982-03-19
Publication date: 1982-11-24
Also published as: GB2098445B; FR2541082A1; BE892554A

Abstract

The invention relates to a method for cultivating non-vigorous plum trees, in which a scion of a known superior plum variety is grafted on the wild plum variety "prunus pumila L", which belongs to the "microcerasus" section rather than the "euprunus" section. The stock is appropriately obtained by cloning seedlings. The result is therefore plum trees which are only approximately 40-50% of the normal growth, from which fruit can easily be removed, which are to be planted closer together and are also immune to Scharka virus. A graft stock variety for plums of the "prunus pumila L" variety from the "microcerasus" section is also claimed.

Description

SPECIFICATION Method for cultivating plum trees The invention relates to a method for cultivating plum trees, in which a scion of a superior variety is grafted on a graft stock (wildling).

Since the cuitivation of plums has been attested by scientific documentation, all superior varieties (round plums, damsons, greengages, Syrian plums and related types) are grafted on socalled graft stocks, also called wildlings, as they cannot be obtained in their true form, the scion of a known superior plum variety being grafted on the graft stock.

According to the international code for cultivated plants, all common eating plums and those which can be preserved belong to the "prunophora" family, "euprunus" section, "prunus" genus and in each case a special subspecies, which follows the actual name of the variety. All these varieties are grafted on saplings, seedlings, runners or cuttings from the "euprunus" section as so-called wildings or graft stocks.

However the use of these graft stocks from the "euprunus" section leads, according to the stock, to considerably tall and broad plum trees, as are widely known from fruit growing areas and fruit gardens.

The fruit can only be removed from these tall trees by manual shaking or by shaking machines.

Owing to the drop, especially from the abovementioned great heights, the quality of the harvested crop is greatly reduced and the latter can therefore usually only be used by the canning and jam industry. The usual hand-picked harvest with quality selection and the use of ladders is no longer payable in view of the present wage rates in industrial states. Furthermore, the ripeness of the harvested crop from the tops of the branches, which are usually too close together, varies; this also results in a considerable reduction in quality.

For these reasons, with respect to the plum varities, increasingly less and more expensive fresh high-quality fruit is suppiied to the consumer market.

The object of the invention is to avoid these disadvantages by cultivating short plum trees which enable high-quality desert fruit to be produced in a simple manner.

Various attempts have been made to cultivate short plum trees, since the use of non-vigorous stocks has led to the desired success in the case of apples and pears, sweet and sour cherries.

However all the attempts in this respect to apply these experiments from related fruit farming to plums have failed, as it proved impossible to find a corresponding affinity between the plum grafts and such non-vigorous stocks. Even the use of modified tree types (hedge or oval tops) did not lead to a basic modification as a result of the excessive vigour of all the stocks from the "eurprunus" section, which has the necessary affinity with the grafts. Overgrowth occurs after several years and the cutting work becomes too expensive.

This is the starting point of the invention, which solves the object according to the patent claims.

The invention makes it possible for the first time to cultivate short plum trees. The considerable eonomic advantage lies not only in the fact that plum trees of this type are easy to cultivate and remove fruit from, but also in that the trees can be planted closer together, while still receiving adequate sunshine. The harvested crop is thus more uniform and it has also become apparent that the plum trees cultivated in accordance with the method of the invention are immune to Scharka virus, as opposed to the plum trees hitherto grafted on stocks from the "euprunus" section. It is therefore not only possible to prevent the destruction of valuable fruit plantations by this dangerous disease, but also unnecessary to spray the plantations, which is an expensive procedure.

The method according to claim 1 enables the plum trees to be more satisfactorily adapted to critical climatic and soil conditions.

The starting point for the cultivating method according to the invention is the wild plum type prunus pumila L", which belongs to the "microcerasus" section rather than the "euprunus" section.

This comes from South East Canada, Western Siberia and China. This plant only grows to 1.5 to 1.8 m, grows in the manner of a shrub, is coldresistant up to -400C and immune to several South West European plum diseases. The wild plant "prunus pumila L", also called "sand cherry" in linguistic usage, is very variable as regards habit, so that the branches sometimes bend downwards and are sometimes more rigid and upright. Young shoots are usually thin, upright, bare and reddish-brown. The leaves have an oval, reversed narrow lanceolate shape, are approximately 3-5 cm long, slightly serrated in the upper half, dull green on top, whitish underneath and bright red in autumn. The flowers are white, arranged in numbers ranging from two to four, approximately 1.2 cm wide, on the wood of the previous year. The flowering time is approximately from the end of April to May.The fruit is oval, 1 cm thick, blackish purple and bitter.

As there is an extraordinary variety of seedlings of the F1 generation of these wild plants, it is advisable to select a clone and to graft this with the known plum varieties, the European, for example.

All grafts were planted in 2.5 1 foil containers in a soil mixture of standard soil P (according to Prof. Frussdorf) with an addition of 20% sand and cultivated above ground from a black foil stock.

There was no subsequent fertilization. Watering was carried out via a standpipe apparatus. The summer graft (inoculation) was also successfully carried out with the same stocks.

Positive results were obtained without exception when testing the affinity of known plum varieties with the "prunus pumila L" stock, hitherto not known in practice. The adnasence of the grafts was completely normal and by autumn all varieties had reached a height of 120 to 125 cm and satisfied customary standards as regards quality.

The decisive result of this cultivation, which took several years, was that all 14 tested superior plants combined excellently and so as to produce a healthy growth with the new graft stock "prunus pumila L", the reduction in the future cloning. The tests showed that, owing to this combination with the short wild plant variety "prunus pumila L", the reduction in the futur growth of the plum trees leads to only approximately 40 to 50% of the usual growth. As a result of this small growth the plum trees can be planted close together, while still receiving adequate sunshine. They are easy to cultivate and to remove fruit from, so that plums of a desert fruit quality can be produced in a simple and economic manner.

It should also be mentioned that seedlings or clone stocks or intermediate grafts from the "prunus besseyi bailly", "prunus tomentosa' Thunb.", "prunus glandulosa' Thunb.", "prunus tenella canadensis' Loisel", "prunus cerasus glauca' Moench", "prunus susquehanae' Jag." varieties are identical to the said wild plum variety "prunus pumiia L" and the same success can therefore be achieved.

Claims

1. Method for cultivating plum trees, in which a scion of a superior variety is grafted on a graft stock (wildling), characterised in that a scion of a known superior plum variety is grafted on the wild plum variety "prunus pumila L", which belongs to the "microerasus" section rather than the "euprunus" section.

2. Method according to claim 1, characterised in that a clone is selected from the wild plum variety "prunus pumila L'' and the stock, on which a scion of a known superior plum variety is grafted, is propagated from this clone.

3. Method according to one of claims 1 or 2, characterised in that an intermediate graft scion of approximately 5 to 15 cm of the wild plum variety "prunus pumila L" is grafted on a graft stock from the "euprunus" section, a scion of a known superior plum variety subsequently being grafted on this scion.

4. Method according to one or more of claims 1 to 3, characterised in that the wild plum variety "prunus besseyi bailly" is used as the graft stock instead of the wild plum variety "prunus pumila L'' from the "microcerasus" section.

5. Method according to one or more of claims 1 to 3, characterised in that the wild plum variety "prunus glandulosa' Thunb." is used as the graft stock instead of the wild plum variety "prunus pumila L" from the "microcerasus" section.

6. Method according to one or more of claims 1 to 3, characterised in that the wild plum variety "prunus tomentosa' Thunb." is used as the graft stock instead of the wild plum variety "prunus pumila L" from the "microcerasus" section.

7. Method according to one or more of claims 1 to 3, characterised in that the wild plum variety "prunus tenella canadensis' Loisel" is used as the graft stock instead of the wild plum variety "prunus pumila L" from the "microcerasus" section.

8. Method according to one or more of claims 1 to 3, characterised in that the wild plum variety "prunus cerasus glauca' Moench" is used instead of the wild plum variety "prunus pumila L" from the "microcerasus" section.

9. Method according to one or more of claims 1 to 3, characterised in that the wild plum variety "prunus susquehanae' Jäg" is used as the graft stock instead of the wild plum variety "prunus pumila L" from the "microcerasus" section.

10. Graft stock variety for plums of the "prunus pumila L" variety from the "microcerasus" section, characterised by a low, shrublike growth, approximately 1 to 2 m high, branches which sometimes bend downwards, young shoots which are thin, upright, bare, reddish-brown; leaves which have an oval, reversed narrow lanceolate shape, are 3-5 cm long, slightly serrated in the upper half, dull green on top, whitish underneath and bright red in autumn; white flowers, from 2 to 5 in number, approximately 1 to 1.5 cm wide, on the wood of the previous year, flowering time from the end of April to May; fruit which is oval, approximately 1 cm thick, blackish-purple and bitter.