Word From The Market with AMA
Due to change in the climatic conditions, the planting periods of maize has been severely affected. In the past, October-November has been regarded as safest as it coincided with early rains. However, lately many farmers have been preferring to plant in December. This has been necessitated by continued development of early maturity seed varieties by seed producers.
Variety selection
When selecting a maize variety there is need to research and consider several factors that include the season length. This can help in determination of the type of hybrid that is needed by the farmer. There are several types of maize hybrids available on the market depending on the season length of an area. These are the early maturing hybrids for short season length areas and late maturing season hybrids designed for area with longer seasons.
Disease resistance is also another factor that a farmer should consider when selecting a variety to grow. Maize varieties differ in their susceptibility to diseases which include maize streak virus and grey leaf spot. A farmer should check the maize susceptible diseases and choose a variety that is resistant to those diseases. In addition, check with the surrounding maize farmers to see if they have any maize crop disease outbreak and buy a variety that is resistant to that disease.
Altitude and the air temperature in your area have a direct effect on the days from planting to flowering and maturity. The warmer the weather, the faster the time taken for crop development and the lower the temperature the greater the amount of time taken for crop development, therefore, affecting the choice of the variety according to the climate.
Other factors that one needs to put into consideration when selecting the variety they want to grow is soil fertility, the amount of fertiliser to be applied, and pest disease occurrence.
The use of integrated pest management in maize
Integrated pest management is the use of all pest control methods that is cultural, chemical, biological methods in a well-organised and harmonious way to achieve long term pest control. It is a pest control method that aims to protect the environment and the ecosystem on a larger scale. It considers the fact that not all pests are harmful to the environment, but some pests are beneficial. Therefore, integrated pest management has set some steps that one needs to follow so that they do not kill the environment.
Firstly, a farmer needs to identify the pests that are in the area and embark on pest prevention methods. Monitoring the pest’s activity regularly if they are destroying the environment or protecting the environment is key. The pest control method that one wishes to use depended on the threshold level.
Threshold level is the population density at which control measures should be done to prevent economic damage. With additional damage to the crop by the pests there are increased economic loses which the crop can no longer compensate for even if it is to recover.
Integrated pest management aims to avoid pesticides which cause harm to the environment and other beneficial pests. It wants to avoid the use of purple triangles and wants to minimise the use of chemicals.
Pest prevention links with the cultural control pest management.
Prevention should be your first line of defence. It involves the selection of resistant cultivars, crop rotations, planting at the appropriate times when there is no pest out break and proper management tools like avoiding overhead watering. One should also practice proper sanitation measures for example cleaning of tools, rouging and the removal of weeds.
After this step, the farmer should scout and monitor the pest activity. Scouting involves checking the field for the presence, population levels, activity size, density of weeds insects and diseases. This will shed light on the tracking of the seasonal pests, compare data from season to season, when to spray and when not to spray and what not to spray.
Monitoring involves four key strategies which include scouting of infected sites, trapping of the actual pests, determining the presence of the natural enemies of pests and lastly visual scouting.
Pest control methods involve the cultural, biological and chemical control. Cultural pest management involves the use of the knowledge of ecology and biology to disadvantage the pest. Cultural methods involve destruction of crop residues. Crop residues harbour pests and this helps to destruct or to destroy their life cycles for example maize stalk borer overwinters in maize stalks.
Leaving the land fallow is also another measure. This starves the pests of alternative hosts and die. Flooding the area is also another cultural control method for it creates anaerobic conditions for the pests. Lastly timing of sowing or reaping, this can be timed so that the crops most vulnerable growth stage does not coincide with the pest peak stage.
Irrigation management is also another practice, adequate water supply ensures vigorous crop growth and in some cases over irrigation can reduce some soil inhibiting pests like eggs of potato tuber moth.
Biological methods are using the crops natural enemy as a defence mechanism to control pests. For example, ladybirds controlling aphids. One can also make use of catch crops, trap crops and companion crops. Companion crops one can use crops like onion and garlic to repel aphids.
Lastly one can use chemical control method which should be the last resort one should take. One can only use this method when the pests have reached the economic threshold level.
Plant spacing
The typical average yields of Zimbabwe are roughly 4 – 6 tonnes/HA. Recommended plant population 55 000 plants per ha
Plant population is an important factor in maize production for it affects overall yield. Plant population is dependent on factors which include the environmental yield and the potential yield of the hybrid selected.
The climatic conditions, the variety and hybrid, amount of moisture available in the soil, the soil type, and the soil fertility characteristics and lastly the fertiliser rate which you intend to apply. If one does not follow the proper spacing, they are risking on their yield and the health of the plant.
If a farmer increases their plant population and it goes above the optimum plant population that is recommended the maize plant will increase in plant height, cob height, its chances of lodging and the plant is exposed to high chances of plant and water stress.
It also leaves room for poor emergence. If the farmer goes below the optimum plant population that is required, they will also decrease the stalk thickness, the cob size, seed size. If one does not follow the recommended plant population spacing, they are exposing the crop to go through all these so it is recommended for a farmer to use.
Word from the market is a column produced by the Agricultural Marketing Authority. Feedback mmlambo@ama.co.zw or gmashiri@ama.co.zw
