Have you ever wondered where the grapes in your wine or juice come from? Kenya is known for its quality agricultural produce but in of grape production, we are a far way off.
Very few Kenyans know where this crop is grown. It has been established that the crop grows well in Naivasha, Mandera, Mombasa and Kibwezi.
The crop is not very exacting about temperature, consequently it can be the grown practically everywhere in the world making it the fruit with the widest geographical distribution.
Kenya has a great potential to be a leading producer of the crop, if its cultivation is taken seriously.
We will save a lot of foreign exchange as over 90% of the fruit used in wine and juice making is imported from South Africa and other countries.
The existing varieties can be classified into two distinct groups according to their functions
1. Table grapes- this group of grapes are used in making various meals for example as sweeteners in cakes.
2. Wine grapes-used specifically in the production of wine.
The crop is a woody perennial vine having the ability, to live beyond 500 years.
There are a number of grape varieties; they include, French grapes also known as Vitis vinifera, American grapes- vitis labrusa and Mediterranean/ Muscatine grapes.
The most widespread grapes species is Vitis vinifera; a native of Europe grown on the world’s most land acreage.
Environmental conditions for grapes.
The crop prefers warm to hot temperatures; during fruiting, the weather must be sunny and dry.
Warm environmental temperatures during fruit ripening, is important in increasing the sugar content of berries while reducing their acidity.
This explains why grapes grown under irrigation in hot deserts or semi deserts are sweeter than those from cold humid areas.
The crop can grow in any soil, from sandy to heavy clays but the soil should be deep and well drained.
Where the rainfall is scant, supplement it with an irrigation of 500 mm of water during the cropping season. In Kenya, the cropping season is September to March.
Irrigation should be withheld after the long rains so as to force the crop to go dormant.
In August to September, fruit buds form thus it is important to keep the plant healthy and well manured.
Suitable scions for Kenya are as follows
Table grapes: Dodrilabi, Black rose, Italia, Muscat of Hamburg, Alphonse, Laralle, Muscat of Alexandria, Perletta, Cardinal, Dalbiki.
Wine grapes: French colombard, Sauzao, Saungnok blank, Carbaret, Alicarte, Grenard, Semillon
Most rootstocks are adapted to many soil conditions. The selection of a suitable rootstock is based on the following criteria;
1. Resistance to Phytphora root rot
2. Tolerance to drought and other soil conditions like low PH
3. Adaptation to soil depth and texture
4. Resistance to crown gall Agrobacterium tumefaciens. This bacterium weakens vines by encouraging the production of large amounts of cytokinins and auxins that induce excessive cell division and elongation.
5. Adaptation to varied PH which affects availability or uptake of nutrients. The scion should be adapted to high PH soils to facilitate absorption of Fe2+ Mn2+ and Zn2+ should be adapted to low PH so as to take in Mg2+, Ca2+ and K+
6. Phyloxera (grape louse) and nematode resistance. Nematodes are vectors of grape fan leaf virus.
7. Vigour control- in cold regions vines exhibit indeterminate growth. Such growth results to the diversion of food reserves to vegetative growth at the expense of the fruit development.