Research
In the area of research and development of VVA-1, Botden & van Willegen bv collaborates closely with PPO in Randwijk (http://www.ppo.wur.nl/).

In 1994, dr S.J. Wertheim was the first to include the VVA-1 in a rootstock test at what used to be the Research Station for Fruit Production in Wilhelminadorp (Netherlands). The conclusion this research yielded was: "Trees on a VVA-1 rootstock are smaller and more productive than those on a St Julien A rootstock." Since then, tests have been conducted by PPO in Randwijk (Fruit Research Unit), which always led to the same conclusions:

  • VVA-1 yielded the smallest tree with the highest production.
  • Until 2003, VVA-1 showed the weakest growth, the fullest blossoming and the highest production with the largest fruit.
  • VVA-1 allows excellent fusion with popular varieties.

The tests mentioned below were realized by the research institute Praktijkonderzoek Plant & Omgeving in Randwijk and funded by the Product Board for Horticulture (Productschap Tuinbouw).

VVA-1

  Victoria VVA-1 2nd year Victoria StJulA 2nd year
  Source: P.P.O. - Randwijk

Objective: To test the practical value of new, weak plum rootstocks.

Test varieties: Avalon and Excalibur.

Objects:
1. St. Julien A
2. VVA-1
3. Ferlenain
4. Pixy

Additional data:
The test was planted in March of 1997, on 3.60 x 2.00 m, in 4 runs of 3 trees per field. To the west of Avalon, a buffer row of Valor and Avalon was planted; Valor being the pollinator for Avalon.

Results
Pixy and VVA-1 rootstocks produce a small tree. With Pixy, the rootstock shows a graft lump, which may indicate a less than perfect fusion of the production variety with the rootstock. VVA-1 has a smooth transition from rootstock to production variety. St Julien A produces a tree characterized by powerful growth.
The leaf analyses of August, 1999 showed low to deficient phosphate, nitrogen, magnesium and manganese contents in VVA-1 and Pixy. More attention is required for the fertilization of these weak plum rootstocks. In 2000, this indication was responded to by means of specific, targeted fertilization, and as a result, the target values in the leaf analyses were achieved this time, for all elements in every object.
New leaf analyses were performed in 2003 in St Julien A and VVA-1. In both rootstocks the target values for all elements were achieved.

Production data of two plum varieties, 1999 until 2003

Avalon kg/tree
1999 t/m 2003		 fruit weight (g)
1999 t/m 2003
1. VVA-1 34,6 56,5
2. St. Julien A 16,7 57,6
3. Ferlenain 12,0 60,0
4. Pixy 19,2 57,7

Excalibur kg/tree
1999 t/m 2003		 fruit weight (g)
1999 t/m 2003
1. VVA-1 16,8 83,6
2. St. Julien A 7,0 82,3
3. Ferlenain 13,6 86,6
4. Pixy 8,6 79,7

The production totals of the trees on VVA-1 were the highest of the rootstocks included in this test. The fruit weights were good, even in high production rates per tree.

Objective: To test the practical value of new, weak plum rootstocks.
Test varieties: Opal, Avalon en Victoria

Objects:
1. VVA-1
2. St. Julien A

Additional data:
The Victoria test variety was planted in Randwijk in February, 2000, on 3.6 x 2.0 m in 5 runs of 2 or 3 trees per test field. Avalon and Opal were planted at a practical testing company in duplicate, with 6 trees per test field on 3.5 x 1.5 m. The plant material consisted of one-year old branched material.

Results: Like in 2002, VVA-1 showed the weakest growth in 2003, while showing the richest flowering and yielding the highest production and the largest fruits.

Production 2001 to 2003

Rootstock kg/tree
'01 to '03		 fr. weight (g)
'01 t/m '03		 % fr. with gum
15-06-2003 		% fr. with gum
10-09-2003
1. VVA-1 12,4 52,3 88 17
2. St. Julien A 4,7 45,8 94 12

Stammen
(Left Opal on VVA-1, right Opal on Ferlenain)

The fusion of VVA-1 with Opal proved exceptionally good (left side). The fusion with Ferlenain, however, is poor (right side). Photo: PPO.