Clonal propagation of eucalypts

KFRI has overcome the problem of low productivity of eucalypt plantations in Kerala to a great extent by identifying and mass multiplying fast growing disease tolerant/resistant clones. The method followed is described below.

Disease tolerant and fast growing candidate plus trees of Eucalyptus tereticornis and E. camaldulensis were selected from eucalypt provenance trial plots and coppiced for producing juvenile shoots. Two leaved cuttings prepared from 45- to 60-day-old juvenile shoots were treated with 4000 ppm indole butyric acid (IBA) mixed with talc and planted in vermiculite medium in root trainers. The root trainers were placed in mist propagation unit specially designed for rooting and sprouting of the cuttings. The cuttings rooted within three weeks. The rooted cuttings were transferred to hardening sheds where watering was regulated. The plants were subsequently kept in open area. Fertilizer (NPK mixture) was added to the vermiculite medium as aqueous solution (0.25%) periodically. Three- to four-month-old plants can be outplanted in the field. There is a four fold increase in the yield from clonal eucalypt plantations.

So far, a total of 1,12,350 ramets of 23 clones have been supplied to Kerala Forest Department and 6,500 ramets of 7 clones to Hindustan Newsprint Ltd., Kottayam, J.K. Paper Ltd., Rayagada, Orissa & TN, UP etc. for raising clonal multiplication area and clonal plantations. These clones are available for sale on cost basis with prior order.

Control of Cylindrocladium leaf blight disease in nursery

The disease is caused by several species of Cylindrocladium. It is most prevalent in eucalypt nursery during heavy rain. The infection starts as greyish brown water soaked spots on the leaf surface, which coalesce rapidly to form large spots. The infection, which begins from the lower leaves, rapidly spreads to the upper leaves and the plants show a blighted appearance. The affected stem may break at the infection site. If unattended, the mortality will be about 100 per cent.

To control the disease, the plants may be drenched profusely with carbendazim 0.05% (a.i.) solution. The treatment may be repeated after 10 days.

Control of damping-off disease in nursery

Damping-off occurs in nurseries of eucalypts, ailanthus and several indigenous species immediately after germination of seeds, if the soil moisture is very high and the environment is warm and humid. The disease occurrence can be minimized by reducing watering. For effective control, carbendazim 0.05% (a.i.) may be applied at least twice as soil drench at an interval of four hours.

Control of pink disease in forest plantations

Pink disease is a plantation disease, which affects 1- to 3-year-old saplings of teak, eucalypts, ailanthus, acacia, bombax, rubber, mango, etc. The disease is caused by the fungus Corticium salmonicolor. Appearance of pinkish white mycelium or pink encrustation over a canker formed at the site of infection is the initial symptom. When the disease becomes severe, wilting of the plant above the infected portion occurs and this is followed by cracking of the bark and formation of epicormic branches below the infected site.

For controlling the spread of the disease, infected branches may be cut and burned. Bordeaux paste (10%) may be applied up to 30 cm above and below the affected region.

Fertilizer application for eucalypts

Fertilizer application is ideally done based on soil analysis report. However, the following recommendation may suit most of the areas with sandy loam to loamy medium acidic soil.

The above fertilizers may be applied in two equal split dozes during the South West (June-August) and North East (October - November) monsoon. First year application may be done in pits and mixed with soil at the time of planting, and the second and third year applications around the plant in 5-10 cm deep furrows made 10-15 cm away from the plant.

Sapling borer attack in young teak and eucalypt plantations

The damage is caused by the larvae of the lepidopteran moth, Sahyadrassus malabaricus Moore. The borer damage is characterized by the external mat of frass and excreta covering the borer hole/affected area.

To control the stem borer, apply quinalphos (Ekalux 25 EC) 0.2% solution in and around the borer hole, after removing the frass cover mat. Dilute 8 ml of Ekalux 25 EC in 1 litre of water to get 0.2% solution. Apply the insecticide during the evening hours, because the larvae come out at night to repair the mat cover. Avoid spraying during rainy days.

Termite control in eucalypt plantations

In forestry, eucalypt is quite vulnerable to attack by termites during the establishment phase. Therefore, seedlings need to be treated using insecticides before planting out. Chlorpyriphos belonging to the organophosphate group is recommended for this purpose. For treating seedlings raised in polythene containers, a solution of chlorpyriphos is prepared by mixing 1 litre of chlorpyriphos 20 EC in 40 litres of water. The seedlings are drenched using a rose can. Care may be taken to aviod spill over of the solution on the leaves. Insecticide solution falling on the leaves can be removed by spraying water. About 120 litres of solution is required to drench about 2500 seedlings. Chlorpyriphos is available in the market under several trade names such as Dursban, Durmet, Dhanvan, Pyramid, Robon, Thrisul, etc.

For root trainer raised seedlings, a slightly different methodology is employed. The root trainer raised seedlings with container, are dipped in 0.5% chlorpyriphos 20 EC solution, before planting out in the field.