Seed Treatment: Advantages, Disadvantages, and Common Pests, Exams of Agricultural engineering

Download Seed Treatment: Advantages, Disadvantages, and Common Pests and more Exams Agricultural engineering in PDF only on Docsity! Illinois seed treatment exam questions with verified solutions. Seed treatment pesticides include - ANS 1. Herbicide antidotes (safeness) 2. Bactericides 3. Insecticides 4. Fungicides Not a seed treatment - ANS 1. Seed applied growth regulators 2. Micronutrients 3. Nitrogen- fixing organisms Advantages of using seed treatment - ANS 1. Control of seed borne pathogens 2. Protect vulnerable seeds and seedlings during stressful conditions of germination and emergence 3. Targeted, low dosage 4. Relatively inexpensive control option 5. Relatively inexpensive control option 6. Reduced environment impact 7. May be only real control option 8. May be an alternative for spraying some early foliar pests Disadvantages of seed treatment - ANS 1. Accidental poisoning of children, animals, and wildlife 2. Potential for contamination of food and feed supply 3. Exposure during application and planting 4. Seed or seedling phtyotoxicity 5. Limited duration of protection (also a benefit) 6. What to do with leftover treated seed Factors that favor the use of seed treatments - ANS 1. Field is for seed production 2. Low test weight or older seed 3. Planting in unfavorable germination conditions such as wet and/or cold soil (these conditions may allow weak pathogens to infect) 4. Planting into fields with a history of stand establishment problems 5. Planting to precise populations 6. Replanting will not be feasible if first planting fails 7. Seed is expensive 8. Seed thought to carry certain seed borne pathogens 9. Yield potential of field is high Seed treatment as part of imp - ANS 1. Help minimize negative effects on the environment 2. Avoid pesticide residue in the food supply 3. Minimize economic loss due to pests 4. Avoid development of pests that overcame pesticides and host plant resistance Purpose of seed treatments - ANS A. control of seed borne pathogens *seed borne pathogens may be found on the seed surface, in cracks and crevices or as infections inside the intact seed * these pathogens may be important for three reasons: 1. some seed borne pathogens may not survive in the soil or on plant residues. 2. Seed borne pathogens may get a head start and cause greater damage. 3. seed borne pathogens may move from one location to another in seed shipments B. control of soil borne and foliar pests *germinating seeds and young plants are relatively tender and lack food reserves to recover from injuries Contact pesticides - ANS control only surface pathogens Systemic pesticides - ANS help control seed borne pathogens both on the surface and internally Alternatives to seed treatment - ANS 1. Crop rotation 2. Good fertility management 3. Heat treatment 4. Planting date 5. Soil applied or post-emergence sprays 6. Controlling volunteer crop plants Fungi - ANS small organisms that are mostly saprophytic (live on dead plant or animal material) but a few are pathogenic (live on live plants or animals) Bacteria - ANS are single-celled organism that reproduce by division Viruses - ANS consist of either Dan or ran with a protein coat Common bunt of wheat (external) - ANS *seeds dark and fish smelling (stinking bunt) *bunted heads stay green longer * persists on seed and in soil *infects coleoptile before emergence Loose smut of wheat (internal) - ANS *fungus lies dormant in the embryo until germination *infected heads form head early and produce spores instead of seed *neighboring plants are infected during flowering Pithier and phytophthora (seedling root diseases) - ANS *fungal-like organisms and are considered water molds (spores swim in water) *they can infect and kill all season as long as soil is wet *they sauce soft rot of seed *phytophtora tolerant and resistant varieties available: 70 races identified in Illinois -tolerance not effective until 10 to 14 days after emergence P a g e 1 | 3 Fusarium seedling blight and root rots (seedling root diseases) - ANS *can infect/damage early or late *symptoms are nondescript, but generally off color to dark black to completely rotted (sometimes pinkish tinge) *infected seeds can result in seedling blight Rhizoctonia (seedling root diseases) - ANS *usually a problem when crop is stressed-soil compaction, dry emergence conditions, herbicide injury. *likes cool, then hot and dry weather Stewart's bacterial wilt (foliar diseases) - ANS *carried by flea beetles: which are more common after mild winters (<27 degrees in Dec. Jan. and fib =no infection; >33 degrees=lots of insects/disease) sweet corn vulnerable *field corn generally has good resistance. *symptoms - long yellowish streaks, parallel to the veins -wilting, may resemble nutritional problems or drought stress. -seedling crown may have chocolate-brown soft rotted cavity at base of plant *control -systemic insecticide seed treatment may reduce this disease. -grow resistant varieties Barley yellow dwarf virus (viral diseases) - ANS *an obligate parasite *vectored by aphids *found along field border or in patches *seedling infection: -winter kill, stunted growth, reduced tillers, and yellow leaves * post-seedling infection-yellow, red, or purple leaf coloration. *fall infection is more important than spring infection *systemic seed treatment insecticides may help reduce barley yellow dwarf virus Seed corn beetles (soil borne insects) - ANS *approximately 1/4" long, light brown to yellowish brown, with a broad black stripe on each wing cover. Attacks sorghum and corn during prolong cool wet weather. Adults over-rated as a problem; larvae considered beneficial Slender seed corn beetle (soil borne insects) - ANS Shiny, dark red in color. Has a constriction. Attacks sorghum and corn during prolong cool wet weather. Adults over-rated as a problem; larvae considered beneficial Seed corn maggot (soil borne insects) - ANS *attacks corn, soybean, sorghum and other crops * damage occurs as the larvae burrow into seed and destroy germ * larvae are 1/4 " long, legless, pale yellow to white maggot that tapers somewhat like a carrot. *adult is a brown fly which lays its eggs in moist soil rich in organic matte (manure applied fields) *several generations per year Wireworms (soil borne insects) - ANS * larvae are shiny. They are pale yellow when small and reddish brown when are larger * corn, sorghum, soybeans, and vegetable seeds and or the base seedlings-often a problem on crops after small grain, sod, or pasture. *use soil insecticides for heavy infestations Chinch bug (foliar insect) - ANS *attacks corn, sorghum and small grains *adults overwinter in grass and move to small grains in spring *nymphs move to field edges next to corn or sorghum *nymphs feed on lower leaves and plant base-entire plant may wilt and turn white *systemic insecticide seed treatment can help control this insect Corn flea beetles (foliar insect) - ANS *attack sweet corn and vegetables *adult beetle is black and 1/16 to 1/8' long *overwinters in grassy areas *adults cause scratch areas on leaves (both sides) parallel to veins -leaves look whitish or silvery *during feeding they may transmit Stewart’s wilt disease Hessian flies (foliar insect) - ANS * attack wheat *they cause damage in spring and fall * damaged plants are dark green, stunted, and easily lodge. *Second generation adults emerge from wheat stubble in late summer/early fall and lay eggs on winter wheat leaves (new crop or volunteer) *larvae feed between leaf sheath and stem and pupate by mid fall. * overwinter as flaxseed like pup aria, and emerge as adults in spring. * Use resistant varieties and plant after the fly free date. *systemic insecticide seed treatment can also be effective consider the following points when choosing a seed treatment product or mixture - ANS * pesticide with appropriate activity may not be available * available pesticides may have little or no systemic activity * available pesticides may not move into the expanding root system *pesticide duration may dwindle too soon (usually 10 to14 days after planting) *effective rates may simply be too expensive or photonic Systemic seed treatments pesticides - ANS *movement into seed, root, and shoot tissue * control of internal and emergence diseases and insects Contact seed treatments pesticides - ANS * no movement into seed tissues * no control of internal pathogens * protects only against external insects and diseases * protection only effective until seed coat breaks P a g e 2 | 3