Nursery Techniques - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 41

out by reducing first the quantity of water in each irrigation and then the irrigation
frequency. This should be planned about a month ahead of taking the plants to the
field for outplanting. Similarly, the plants that have outgrown in size and are likely
to coil their roots in the pots should be given less than the usual amount of irrigation.
In extreme cases, irrigation should be stopped for a month or so.

2.12 Weeding and Cleaning

Weeds come with manure, clay, or sand transported into nursery from outside. Some-
times undesirable seeds get mixed with the seeds sown. When weeds have grown and
become visible and identifiable, these are removed by pricking out. If two seedlings
of the species sown have come up in a pot, one of these should be immediately
pricked out and transplanted into another polypot that does not have a plant. If any
clutter or muck fills up the (upper part of) pots, the pots should be cleaned. In mother
beds, it is also desirable to hoe the soil periodically, apart from removing the weeds.
These seemingly simple operations matter a great deal in determining growth of the
plants.
Weeds may pose a more serious problem if it is unavoidable to use clay or sand
infested with weeds. In such a case, a flood irrigation is given to the polypots a couple
of times and weeds allowed to germinate, after which all the weeds are destroyed by
pricking out. Seeds are then sown into the pots.

2.13 Protection from Insects and Pests

Termite, or the white ant, and other pests may pose a risk to plants in mother beds.
Pests are less likely to affect plants in seedbeds and pots because the period for which
the plants are kept at one place is short and the soil is confined. However, if the risk
cannot be avoided because of the use of termite-infested clay, sand or manure, the
potting mix should be treated with pesticides.
Fungal attack on the roots of plants and leaf defoliators are the common pests
affecting containerised plants in a nursery. In case of a fungal attack, appropriate
fungicide in liquid form should be given in between irrigations. Foliar spray of
suitable pesticide (Table 2.8 ) should be administered to contain defoliators. A pes-
ticide should not be mixed with the regular irrigation water because that will bring
concentration of the pesticide down to an ineffective level.
Each pesticide has a lower threshold of concentration below which it is not effec-
tive, whether it acts as a repellent or by killing the pest. Therefore, the recommended
dosage in administering pesticides should be adhered to. If used in powdered form,
the pesticide powder should be mixed with soil thoroughly. In liquid form, it should
be diluted to the recommended concentration and the affected soil should be irrigated
with it, or if used externally, plant shoot should be sprayed over with the help of an