Nursery: Maintenance

Watering

The most important factor in achieving good success in the nursery is the availability of sufficient water to ensure optimum growth of the seedlings. More often than not inadequate watering is the root of pest and disease problems in the nursery as the seedlings would be at a weaken stage and therefore more prone to pests and diseases. A good indication of inadequate watering in the nursery is the incidences of collante and blast disease.

Poor or uneven coverage of the irrigation system may also lead to seedlings of poor uniformity. This is a very common fault in nurseries. Watering must be done daily including holidays.

With the current technology of irrigation system in the nursery either by overhead sprinkler system (OSS) or lay flat sprinkler tubes (e.g. Sumisansui, photo 5 & 6), the watering should be carried out twice a day for 45 minutes each time, to supply 8mm of water daily. A rain gauge may be used to check whether the amount of water supplied is sufficient.

Manuring

It is well established that the fertiliser rates for nurseries require adjustment to varying management practices and according to different soil types (Hew & Toh, 1973). However the recommendations and system described in this paper are based on sandy clay loam, inland soils for general usage and on conventional fertilisers or controlled/slow release fertilisers.

Manuring programme based on conventional fertiliser

Fertilisers are not required until one complete new leaf has appeared (4 -5 weeks after planting). Use of conventional fertiliser should preferably be confined to small nurseries for field plantings of less than 50 ha or areas with adequate labour. The programme is given in Table 2 below:

Fertiliser application

For foliar application, the drenching of the seedlings with foliar fertiliser solution should be carried out early in the morning or late afternoon. As far as possible, the whole seedlings should be wetted and no watering of the seedling should be carried out for the day of application. However High Grade Fine Borate Compound ( HGFB ) solution application for large polybags should be done after normal watering.

For solid application, the compound fertiliser should be weighed to obtain the correct rates, and calibrated applicators (e.g. scoop, spoon, etc.) given to the workers to ensure that the correct rates are applied. The fertiliser should be evenly distributed on the surface of the polybag soil at least 2-4 cm away from the base of the seedlings. The application of solid fertiliser should be carried out when the seedlings are dry, i.e. in the morning before watering, or in the afternoon after the morning watering.

Good supervision of all fertiliser applications is necessary to obtain full benefits from the inputs.

Manuring programme based on slow release fertilisers

There are many types of slow release fertiliser (SRF) currently available in the market. The SRF selected for use should supply the required nutrients at the right time and amount to the seedlings for good growth.

Fertiliser rate

The general recommendation for use of SRF in the nursery is provided in Table 3 .

Fertiliser application

The SRF should be spread evenly and buried at 10 cm below the soil surface.

Supplementary fertilisers should be applied from the 9^th month onwards or even earlier if the seedlings show symptoms of deficiencies like yellowing, etc.

Corrective fertiliser application

With the use of SRF, it is essential to monitor the colour and growth of the seedlings regularly due to the long interval without any other fertiliser application. In cases of wrong or inadequate application as indicated by seedling colour and vigour, fertiliser supplementation is required as per conventional fertiliser programme for the appropriate seedling age provided in Table 2.

Culling

Culling is one of the most important procedures to be carried out in the nursery to ensure that only the most uniform and vigorous palms that are likely to give the highest yields are planted in the field.

Four rounds of culling are recommended during the nursery period. In addition, a final round of selection should be done just before field planting.

Culling in the pre-nursery stage

Culling at the pre-nursery stage is carried out at month 2 and prior to transplanting the main nursery at around month 3 to 4.

This is one of the main advantages of the double stage nursery system where the first stage culling of undesirable palms can be done stringently and quickly over large number of young seedlings. The main types of undesirable seedlings (should be culled) at this stage are as follows: narrow (grass leaf), rolled leaf, twisted leaf, crinkled leaf, collante and stunted or weak (runts) palms. Allow for 10 to 20% culling at this stage.

Culling in the main nursery

Culling in the main nursery should be carried out when the seedlings are 7 months and 9 months old while the fronds of neighbouring palms have not started to overlap and etiolation not set in to mask the runts. The typical characteristics of abnormal seedlings in the main nursery are as follows: –

Erect, flat top, broad pinnae, narrow pinnae, wide internodes, juvenile (slow to pinnate), weak and slow growing (runts), crinkled leaf, collante, chimaera, badly diseased (helminthosporium, curvularia, blast, crown disease) and palms badly damaged by chemicals.

The final round of selection based on uniformity and vigour should be carried out just before the seedlings are being loaded onto lorries/tractors for transport into the field. If planting is delayed the final round of culling must be carried out before etiolation sets in. Allow for 5 to 10% culling and selection for the main nursery.

Timely culling rounds will ensure the unnecessary keeping of unwanted seedlings and reduce costs in the nursery.

Recording

Accurate records of discarded seedlings are necessary to ensure that adequate seedlings are available for field planting and supplies.

Pests and Disease Control

This is another important aspect in oil palm nursery management. Pest infestations and disease infections can cause alarming damage and losses if not recognized at an early stage and brought under control quickly. Most pest and disease problems can be avoided by correct agronomic and management practices, but where they are unavoidable, early detection and prompt control measures are crucial.

Common pests and diseases in the nursery

Common pests in nursery are red spider mites, leaf-eating caterpillars, cockchafers, grasshoppers and rats. The common diseases are mainly fungal leaf diseases like curvularia, cercosporium and helminthosporium.

Pest and disease control

There are a number of measures which if implemented can assist in reducing the incidence and severity of pest and disease attack in the nursery. The key to good P and D control is vigilance and prompt action to contain the problem.

Prophylactic spraying

Routine prophylactic spraying is not necessary if the seedlings are growing vigorously and the nursery is well managed.

However, where nursery palms are sub-optimal in growth and vigour, fortnightly prophylactic spraying of fungicides and insecticides may be carried out until palms return to normal growth.

Pesticides may be mixed with foliar fertilizer mixtures in a single application but these should be confirmed with the supplier if in doubt.

Spraying should preferably be carried out in the evening after the last watering.

Training of nursery workers in pest and disease recognition

It is certainly worthwhile to train nursery workers to recognise the symptoms of common pests and diseases in the nursery and report them. This outbreak reports by people who are working full-time in the nursery will provide an “early warning” system to the management.

Weeding

Weeds in the nursery area should be eradicated since some weeds may harbour pests or are hosts for diseases. It is necessary to keep the polybags completely free of weeds that would compete for nutrients, moisture and sunlight. Ideally the nursery should be weed-free.

Weeding in the pre-nursery stage

In the pre-nursery where seedlings remain for only 12-16 weeks, very little weeding is required. When necessary, hand weeding in the inter-bed paths and within the small polybags should be carried out monthly.

It is generally recommended that all herbicides be avoided at this stage in view of the fact that any error can lead to serious seedling damages or losses.

Weeding in the main nursery stage

Mulching with palm kernel shells can greatly suppress the growth of weeds in the large polybags and any weeds appearing can be quickly and easily hand-weeded.

However, weeds on the ground and surrounding nursery area should be eradicated through chemical spraying as and when required. Only contact herbicides eg. paraquat should be used.

Storage of Chemicals and Equipment

The control of chemicals in the nursery is of the greatest importance. Many instances have occurred of herbicides being incorrectly utilised by mistaking them for insecticides or fungicides. In view of this problem it is strongly recommended that the estate have a separate nursery store and within the store, herbicides are kept separated from pesticides/foliar fertilizers in lockable cupboards. It is also important that nursery equipment used for spraying pesticides and herbicides be also clearly marked and kept apart in separate storage compartments to avoid costly mistakes of cross contamination. They should only be used in the nursery. Empty herbicide and pesticide containers should be discarded and not reused.

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