Training and Pruning
- Plums are generally trained on the open center system or to modified central leader system depending upon the varietal growth habits.
- The varieties with spreading habits of growth as in Japanese plum should he trained to open center system.
- In HP open center system is followed irrespective of variety. However, in the plains, where plenty of sunlight is available, trees should be trained in the form of modified central leader system with 4-5 scaffold branches
Open Centre System
- After planting, the plant is cut back to 40-60 cm above the ground level. During the growing season, about 3 to 6 laterals, in addition to the Central leader, are produced on the tree.
- In the first winter pruning, 3 to 5 scaffold branches which are well spaced and have wide angle should be selected and remaining branches are removed. The Central leader is also completely removed.
- The selected branches are headed back to ¼ of the growth. During the second dormant pruning, 2-3 secondary branches are selected on the primary branches.
- The major consideration in selecting secondary branches should be their location so that after pruning, the tips of primary and secondary leaders are about 30-40 cm apart from each other.
- The height of secondary branches is staggered in different years by pruning all branch leader more severely. The vertical ones are pruned more severely. This will produce branch leaders at different heights and prevent over crowding when the tree is mature.
- In the following years the head should be fully formed and selection of secondary branches are completed.
Pruning
- In plums, thinning and heading back of shoots are two basic components of pruning.
- Most of plum varieties bear on spurs on two years old wood. The life span of these spurs is 5-6 years. It is necessary to prune for some spur renewal each season .
- The extent of pruning is done such a way to induce an annual shoot growth of 25-50 cm.
- In bearing plum trees, 25-30 percent thinning of shoots and 50-75 per cent heading back of shoots is suggested for proper fruiting.
- At the time of pruning , dead ,diseased and broken branches should be pruned off.
Nutrition
- Plum requires adequate amount of nutrients for better growth and quality fruits.
- Application of manures and fertilizers depend upon soil fertility, type of soil, topography, age of tree, cultural practices and crop load.
- The requirement of fertilizers varies from region to region.
- The farmyard manure along with full dose of P and K should be applied during December and January. Half dose of N is applied in spring before flowering and remaining half a month later.
Irrigation
- Plum is mostly grown under rain fed conditions. However, in order to produce a fruits of good fruit size and better quality irrigation is essential.
- Various methods of irrigation are adopted to irrigate plum orchards but in hills basin and drip irrigation methods are more popular and are widely used and recommended.
- After fruit setting, the plum trees are irrigated at weekly intervals and 6 to 8 irrigations are recommended for higher production of quality fruits in Santa Rosa plum.
Orchard floor management and Weed management
- In plum orchard, sod culture and mulching of tree basin area with hay mulch or black alkathene mulch is the most common method of orchard floor management.
- During pre-bearing stage, intercropping with leguminous and vegetable is also practiced in orchards planted in flat and less sloppy land.
- The weed removal manually is one of the practices employed in the orchards besides inter cultivation and cover crop growing. In rainy seasons, the weeds in plum orchard is controlled with the post -emergence sprays of glyphosate at the rate of 800 ml/ hectare.
Crop regulation and Quality improvement
- Generally plum tends to bear heavy crops and bear under sized fruits of low-quality, thinning therefore, is necessary to increase the fruit size and uniformity in colour of fruit and to stimulate flower initiation for the regulation of next year's crop.
- Various methods viz; hand, mechanically and use of chemicals are used but chemical thinning has superiority with respect to thinning cost, fruit size and quality. NAA at 20 to 40 ppm sprayed after petal fall resulted in good fruit thinning.
Maturity, Harvesting and Yield
- It has been observed that plum usually ripen unevenly over the tree. Fruits, therefore, are harvested in two or three pickings and it is very important to find out the exact stage of picking when they are mature.
- Among various indices of maturity, most commonly used are flesh firmness 5.9 ± 0.45 kg, days from full bloom (94±3), TSS 13.5-14.5 and TSS acidity ratio 1.2: 1.5.
- The fruits are harvested with stalk intact avoiding any skin injury.
- Fruits are very delicate and perishable, therefore picking baskets should be lined with soft material on the inner surface.
- Immediately after plucking the fruits should be kept under the shade of the tree to remove field heat.
Grading and Packing
- To obtain high price in the market the grading of the fruits is done to have uniform size and better quality. The packing and grading standards of the plum are:
Storage and Marketing
- Plum being perishable have very short shelf life.
- In India work in HP has revealed that plum can be stored for 1 to 2 weeks at 0°C with 80-90% humidity.
- The CA storage has been practiced overseas by maintaining 2-3% oxygen and 2-8% CO2 and the fruits can be retained for a duration of 2-3 months.
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