Define the term nursery as used in crop production[2marks] (b) Give three reasons for…

Explanation

(a)Definition of nursery in crop production: Nursery is a place where young plants are raised under intensive management practices for later transplanting into permanent fields/plot 

(b)Reasons for establishing a nursery in crop production 
– Promotes economy of seeds/efficient utilization of seeds 
– Seedlings receive more intensive care e.g watering manuring and protection from animals, disease and pests 
– Creates an opportunity for selecting healthy, vigorous and disease-free seedlings for transplanting  
-Seeds that ate difficult to germinate in the field are better raised in the nursery e.g carrot, cabbage. 
– Horticultural practices like budding, grafting are easily carried out in the nursery 
– It is place for hardening delicate seedlings before transplanting them 

(c)Characteristic of weeds that make them difficult to control 
– Ability to produce many seeds 
– Weed seeds have long period of dormancy 
– Some weeds have deep root systems used for absorbing water from deeper horizons in dry soils 
– Some weeds have modified root system for storing food which they thrive on for long periods e.g waterleaf 
– A good number of weeds have very efficient means of dispersal 
– Weeds survive under marginal/poor soil by virtue of profuse rooting systems and their minimum nutrient requirement status 
– Some weeds have very fast growth rates 
– Weeds survive under adverse environmental conditions by means of structures such as stolon, rhizomes 

(d)Methods of controlling weeds 
– Physical/Mechanical control 
– Chemical control 
– Biological control Cultural control 

(e)Ways by which diseases are spread among crops 
– Wind 
– Water 
– Contact(animal and human)
 – Infected/diseased planting materials 
– Infected soils 
– Vectors 
– Contaminated farm tools 

(f)Effects of diseases on crops 
– Reduced yield/output 
– Reduction in the quality of produce 
– Malformation of plant parts (gall formation, reduction in the leaf area) 
– Death of plants 
– Retarded growth of crops 
– Reduced seed viability 
– Deterioration of stored produce