DISEASE ORGANISMS OF CROPS
Classification of crop insect pest into main feeding groupsA pest is an organism which causes damage to crops.
Insect pest are those insects that cause physical damage to crops. Insects belong to the group arthropoda. Generally pests reduce crop yield both in quality and quantity. 1. Biting and chewing insect pest The mouth parts of pests in this group are especially adapted to biting and chewing of various plant parts. The mouth parts are made up of two hard biting jaws (mandibles). In addition to these, they also have two jaws (maxillae). They have two lips – flat upper lip (larum) and lower lip (labium) while the maxillae are used to push the crop parts into the mouth, the mandibles are used for the biting and chewing since they are very strong. These insects can feed on any part of the plant including leaves, fruits, stems, flowers and even roots. Some common biting and chewing insect pests are beetles, grasshoppers, termites, crickets, caterpillars of moths and butter flies, locust, army worms and so on. They feed on many crops such as okro, maize, rice, vegetables, cassava and fruit trees. DIAGRAM Figure 2.8.1a: Cricket DIAGRAM Figure 2.8.1B: Beetle DIAGRAM Figure 2.8.1c: Grasshopper DIAGRAM Figure 2.8.Id: Caterpillar 2. Piercing and Sucking Insect Pests The mouth parts of these insects are shaped tike injection needles and are thus adapted to piercing (that is penetrating into the plant part) and sucking (that is removing plant fluid). These piercing and sucking habits of the insects lead to] destruction of plant tissues, development of holes through which disease organisms can enter into the plant system and transfer or harmful germs from diseased plants to healthy ones. All these lea to weakening and eventual death of the plants affected. Good examples of piercing and sucking insect pests are aphids (plant lice), cotton stainer, mealy bugs, capsid bugs, and scali insects DIAGRAM Figure 2.8.2A: Cotton Stainer DIAGRAM Figure 2.8.2b: Aphid
Boring insect Pests of cropThese are insects that bore into plant tissues and seeds, kamples are stem borers of cereals and weevils such as beans, rice M maize weevils. Other insects pests which may not fall into the above groups have been found to affect crops. An example is the weaving insect which causes the folding of the leaves of crops particularly vegetables. DIAGRAM Figure 2.8.3: Bean Weevil NO. NAME OF PEST CROPS AFFECTED NATURE OF DAMAGE TO CROPS PREVENTION AND CONTROL MEASURES 1 Stem borer (Sesamia spp) Cereals e.g. rice, maize sorghum Pest eats up the juicy centres of stems thus causing the crop to collapse and die Burn all crop remains in the farm after harvest, uproot and burn affected crops. Spray with gammaling 20 or DDT. 2 Army worms Grain crops e.g. Rice, Maize, Sorghum They eat up the leaves and stems of the crops leading to mechanical damage of crops. Plant early. Spray with an insecticide such as gammalin 20.
Ear worms MaizeThese larvae bore into the cobs or ears of maize thereby eating up the fresh grains Early planting spray with gammalin 20 4 Aphids Cocoa, groundnut, cowpea They bite and pierce through the outer texture of growing plants. Sucking out the sap leading to stunting, distortion and defoliation in affected plants Spray affected crops with insecticides 5 Pod Borers (Maruca tesulalis) Legumes e.g. Cowpea They cause damage to the tender parts of the plants, by eating up the flower buds and pods. This leads to reduction in yield. Plant with resistant varieties. Spray with gammalin 20 or diagram. 6 Variegated Grasshopper (Zonocerus variegates) Yam, vegetables, rice, cassava, etc. Eats up leaves of plants. Growing point and stem may be eaten too. Spray with gammalin 20 or vetox 85 7 Yam Beetle (Heteroligus meles) Yam Feeds on tubers of yams in the soil causing holes on them Dust yam planting materials with aldrin dust before planting. 8 Cassava mealy bug (phenacoccus Manihoti) Cassava Affected plants become stunted since the internodes are reduced. The tip begins to develop bunchy tops, the leaves die off finally, the whole plant looks like a candle stick. Plant early. Dip cassava cuttings in 0.1% Rogor or ultracide solution for 1 minute before planting 9 Capsids Cocoa The insects attack young shoots of cocoa and introduce toxic saliva into the plant. This kills the plant Spraying with gammalin 20 10 Cotton stainer (dysdercus superstitious) Cotton Attacks opening cotton bolls thus staining the lint Spray with insecticide 11 Weevils Rice, maize, beans Eat up the cotyledons of stored products Spray with insectitide 12 Fruits worm The larva eats up the fruits Spray with vetox 85 13 Termites Oil palm, cassava, sugar cane, yam, etc They destroy roots and seedlings of plants especially when young Spray with aldrex 40. Water crops regularly in the dry season. 14 Boll worms Cotton They eat up succulent boll. Bolls drop off prematurely Pick and burn affected bolls. Spray with insecticides 8.3 Other Pests of Crops 1. Bird These attack mainly grain crops such as maize, rice, sorghum and barley. They also attack fruits in the field. Examples of these birds are Weaver birds (Quela), parrots, etc. DIAGRAM Figure 2.8.4: A
Nature of disease Damage to cropsThey peck out planted seeds, eat up grains on the field and destroy leaves of some plants such as oil palm. They also eat ripe fruits such as pawpaw, mango, and cashew. (b) Control: 1. Use of scare crows 2. Spraying chemicals such as furadan with aircraft, 3. Shooting with catapult or gun. DIAGRAM Figure 2.8.5: Scare Crow for birds and mammalian pest in farms. 2. Rodents These include rats, grass-cutters, African rabbits and hare. DIAGRAM Figure 2.8.6: A Rodent (Grass-cutter) (a) Nature of Damage: They cut down and eat various parts of the crop especially cereal and tuber crops. Grass-cutters eat up rice, young palm seedlings and maize plants. Rats eat up stored produce like tubers and grains. Hare eat up planted grains. (b) Control: (i) Use of poison baits (ii) Use of traps (iii) By shooting with guns, (iv) Use of rat gums.
Mammalian Pests of cropThese include monkey, deer, antelopes and bush pig. They do a lot of damage to crops in the farm by uprooting eating them up. For example, monkey eat up plantains, banana maize and cocoa pods. Control: (i) Trapping (ii) Shooting with gun. DIAGRAM Figure 2.8.7a: Monkey DIAGRAM Figure 2.8.7b: Giant Rat (Cricetomys gambianus). STUDY QUESTIONS 1. How can insect pests be classified using their feeding habits? 2. (a) Name 10 insect pests you know. (b) For each one, slate the crop it affects, the damage done to the crop and control measure of the pest. 3. (a) Apart from insect pesis, mime three other pests you blow. (b) Which crops do they affect? (b) flow can they be controlled? 4. Classify the following into hiling and chewing piercing and sucking, and boring insect pests:- Beetles, Aphids. stem boreres, caps ids, weevils, locusts, mealybugs, crickets, cotton stainer, 5. Itemise >>>>> you would use for rodents attack on your farm.
here are some useful post for you
1. DEVELOPMENT OF AGRICULTURE
2. IMPORTANCE OF AGRICULTURE
65. PHYSICAL WEATHERING
66. CHEMICAL WEATHERING
85. RETENTION OF WATER BY VARIOUS SOIL TYPES