|
Most favorable conditions for growing
|
        |
 |
 |
 |
Tree nursery management
Importance of the tree nursery
The establishment and management of the tree nursery is the first and most important stage of the growing process because producing healthy and vigorous plants depends principally on this step.By obtaining healthy plants from a protected growing tree nursery, we achieve a greater uniformity, and a reduction of time and costs. But also, we plan fruit supplying and lengthen the fruit productive cycle in the same period of time in which plants were in the protected growing tree nursery free from plant louses and aphid insects' attacks.
In the production of plants at the protected tree nursery, it is essential to consider certain factors such as seed quality, substrate, container, light, humidity, temperature and other managements (the use of fungicides, foliage fertilizers, irrigation, insecticides, etc.)
The tree nursery must be built as close as possible from the planting and as faraway as possible to old papaya plantations (at the very least 1.5 kilometers) to avoid the excess of plants' handling.The tree nursery can also be used as a greenhouse of protected growing. However, it will depend on technical accuracy that is expected to apply.
Types of substrates to use
Substrate is a soil mixture in which the seed is going to be sowed. It is widely known that every material is potentially useful as a medium if it is adequately prepared and managed during the process. This management is strongly related to the irrigation process and to the physical properties of the medium, but also it is related to the functionalism of plants which are grown and to the climate conditions where plants grow.Most growers use alluvium soil (sandy) such as "Topuri" (from Michoacan, Mexico), "Cuelilla y Yocuela" (from Oaxaca and Guerreo, Mexico) and "Tierra lama" (in other Mexican states). This soil can be used to fill bags mixed with organic matter and "tierra pesada" (very clayish). Proportionally, mixtures are standardized 1:1:1; it means 33% of sand, 33% of organic matter (cattle dung, dead leaves, among others) and finally, 33% of soil.
There are trademark substrates for seeds' germination and plantlet production. When marketed substrates are used to produce plants on trays, the most common are made of Sphagnum peat (peat moss) such as Sunshine Mix No. 3, Germinaza Plus and Cosmo Peat among others.
These substrates can be mixed with organic matter (it must be rotten, dry and sifted) and alluvium soil in order to achieve a better yield and good results. Generally, these marketed substrates are supplemented with minerals and optimal PH (PH 5.5 to 6.5).
The substrate, which is used for sowing, helps the growth environment of the radical system and also the supplying of water and light (necessary for an optimal growing of the future plant). Therefore, disinfection of substrate is important when we use soil whether pure or mixed with organic matter (cattle dung, dead leaves, bagasse, among others). It is common that soil is the habitat of many living things and most of them can be harmful for papaya growing, such as fungi, field pests (particularly nematodes) and weed seeds.The most common agrochemical product, used for the disinfection of substrate, is methyl bromide (gas) using 1 pound / m3 of soil. The substrate must be covered by plastic in order to assure its disinfection so that gas is spread uniformly. Its application must be done very carefully because it is toxic. It is applied by using a dispenser. The substrate must be covered during from 48 to 72 hours and it must be exposed to air during 24 hours.
Another method of substrate disinfection is the use of Furad? 350 L ?(Carbofur? 33.21%) in 500 milliliters per 200 liters of water added with Captan ?(Capt? 50%) ?Tecto 60 ?(Tiabendazol 60%) in 300 grams respectively.
It is also possible to use effectively Furad? 350 L ?(Carbofur? 33.21%) at a rate of 500 ml + Previcur N ?(Propamocarb clorhidrato 64%) and Derosal 500 D ? (Carbendazim 43%), at a rate of 250 ml and 200 ml respectively, all in 200 liters de water.
The disinfection must be performed one week before sowing and it is added with 50 milliliters of the mixture of each bag. These bags need perforations to permit good drainage. After applying the mixture, it is important to scatter all bags for the percolation of product so that substrate is disinfected.
Type of container for sowing
The use of a 300-400-size 15 x 20 cm tree nursery black bag is important so that plants achieve an appropriate growth of the radical system. Nevertheless, when it is not possible to obtain this type of bags, it is acceptable to use 12 x 20 cm., 13 x 25 cm. ?10 x 20 bags, but their minimal length is 15 cm.Even if other materials can be successfully used, such as polystryrene trays or plastic glasses, we suggest to use for sowing 60-78 cavity trays so that plants receive sufficient light. It also allows plants to have an acceptable foliage growth.
12-15 size 300-500ml plastic glasses are recommended to use.
Either bags or glasses must have perforations in order to drain the excess of water. All containers should have a dark and opaque coloration.
Container filling and flowerbed making
When Sphagnum peat or peat moss marketed substrates and polystryrene trays are used, it is important that the substrate is moistened before container filling. Approximately 100 liters of water will be needed per 3.8 feet3 bulk.When bags or plastic glasses are used, soil or substrate should be relatively humid in order to make the filling easier as well as seed sowing.
Two centimeters should be left from the rim downward the container to to close the lid easily.
The arrangement of containers should permit free access to the planting activities that is why it is recommendable to leave 40-60 centimeters between flowerbeds. The flowerbeds' width is normally 80-120 centimeters and its length is even 20 meters.
Before sowing, bags are placed in the tree nursery, a thick and black plastic cover should be put on the soil to avoid penetration. Flooding must be avoided during planting.
When trays or glasses are used for the planting process, it is important that containers do not get on the floor.
Pre-germinated seed sowing
This is a very important process because a wrong management can cause a significant losses of plantlets.Pre-germinated seeds should be transported in trays covered with flannel to avoid dehydration.
Seeds must be sowed to a 1 centimeter depth by putting one seed per bag (before sowing, containers should be humid). Once the seed is sowed, it must be covered with disinfected soil and then bags are watered and covered with fodder or paper. When first plantlets' shoots are visible, covers must be removed.
To keep humidity inside bags, it is important to consider climate factors. In case of not considering climate factors, there may be losses of plantlets.
When soil is used as the substrate and not disinfected with methyl bromide, sprouting weeds should be eliminated.
Tree Nursery Protection
There are many ways of protecting the tree nursery, one of them is to use plastic tunnels or straw matting etc. installed as a shed or means of protection against wind.
Light control and regulation
In order to regulate light while plants grow, plastic shed can be used, but in case of plythene greenhouse, light should be regulated in accordance with plantlets' growth.Around the tree nursery, it is advisable to install plastic sheds against pests and animals.
In order to control light and to protect tree nursery against pests more effectively, shadow-proof meshes or sheds can be used to have a 50-60% light control.
Tree Nursery Irrigation
The frequency of this activity depends on the type of substrate, plant size and the environment where the tree nursery is.Tree nursery plantlets should have a constant humidity so soil or substrate has to be in good conditions.
Running or natural water can be used to water, but never saline or high chlorine waters among others.
Soil and foliage fertilization
In order to achieve an optimal plant growth, a 08-24-00 formulation should be applied at a rate of 1 ml / liter per agua. To estimulate the growth of radical system, a rooting stimulant such as Raizal 400 ?a can be used at a rate of 0.5 - 1 Kg. in 100 water liters when 3-5 leaves appear. Additionally, a total foliage fertilizer such as Bayfolan forte ? can be used at a rate of 2-3 ml./ lt. Water, depending on the nutritional level that plants demonstrate. It is important that products do not remain on leaves, so application must be done before irrigation. A 20-30-10 formulation can also be used at a rate of 1 a 2 grams per water liter if plantlets have chlorosis.Since this stage, plants should begin to acclimate without shadow, so sheds should be remove progressively.
Disease control
When it is needed as a preventive treatment, mixtures can be applied in the plant collar.After 10 days of emergency presence, it is important to prevent damping off or rotting by the use of:
- Previcur N (Propamocarb hydrochloride 64%) + Derosal 500 D® (Carbendazim 43%) at a rate of 1 ml. / water liter respectively.
In order to prevent and control fungi diseases, fungicides should be applied alternately, for instance:
- Cupravit ® (Oxicloruro de cobre 85%) 2-3 gr. / water liter
- Benlate ® (Benomilo 50%) 1 grs. / liter
- Manzate ® (Mancozeb 80%) 2-3 grs. / liter
- Derosal 500 d ® (Carbendazim 43%) 1 - 1.5 ml. / water liter
- Tecto 60 ® (Tiabendazol 60%) 2-3 grs. / liter
- Captan ® (Captán 50%) 2-3 grs. / liter.
They should be applied weekly in a preventive way, depending on the salinity level that plants have.
Pest Control
In order to prevent white mosquitoes and other acaruses, some products can be used, such as:
- Herald 375 ® (Fenpropatrin 38.5%) 0.5 - 1.0 ml. / liter
In order to control cockchafer grubs, larvae, whiteflies, thrips, among others, some products can be used such as:
- Thiodan 35 CE ® (Endosulfan 35%) 1 - 1.5 ml. /water liter
To control whiteflies or aphids:
- Rogor 400 ® (Dimetoato 40%) 1 - 1.5 ml. / water liter.
To control whiteflies:
- Confidor ® (Imidachloprid 30.2%) 0.6 - 0.8 ml. / water liter (before transplanting).
 Print this page |
 Print all section |
