(a) Define the term nursery as used in crop production[2marks] (b) Give three reasons for establishing a nursery in crop production.[3marks] (c) Mention three characteristics of weeds that make them difficult to control [3marks] (d) List two methods of controlling weeds.[2marks] (e)State three ways by which diseases are spread among crops [3marks] (f) Mention three effects of diseases on crops [3marks]
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