Will you raise 300 bushels per acre by passing this ultimate corn grower’s challenge quiz? Probably not. Will you find one helpful idea? Odds are you will.
The questions and answers are based on information in the Purdue University Corn and Soybean Field Guide 2018 edition, published by the Purdue Crop Diagnostic Training and Research Center.
1. The first part of the corn plant to emerge is:
a) coleoptile b) radicle c) growing point d) apical meristem
2. The first true leaf that emerges has a:
a) pointed tip b) square tip c) rounded tip d) W-shaped tip
3. If you stage corn growth with the droopy-leaf method vs. the leaf-collar method, stage of growth will be:
a) the same b) one stage behind c) one stage ahead
4. If daily maximum temperature is 68 degrees F and minimum temp is 41 degrees, the growing degree day accumulation for that day is:
a) 19 b) 9 c) 45 d) -4
5. Since planting, 900 GDDs have accumulated. What growth stage should corn be in?
a) 9.5 b) 6.5 c) 7.5 d) 10
6. The most critical time for root establishment is:
a) emergence b) emergence through V2 c) emergence though V6 d) tasseling
7. Mature corn plants rely on which roots?
a) seminal b) mesocotyl c) radicle d) nodal
8. If you shake an ear at pollination and silks fall off:
a) pollination is complete b) pollination hasn’t started c) pollination is 50% over
9. Dough stage occurs about how many days after the R1 stage?
a) 5-7 b) 10-12 c) 24-26 d) 31-33 e) 55-60
10. Purpling occurs when:
a) sugars accumulate in the plant b) soil is compacted c) phosphorus is low d) all of these
11. If you plant April 30 and have a final population of 20,000, what percent of optimum yield can you expect?
a) 74 b) 80 c) 92 d) 99 e) none of these
12. If you plant May 30 and have 32,000 plants per acre, what percent of optimum yield can you expect?
a) 100 b) 92 c) 87 d) 81 e) none of these
13. Hail destroys 60% of leaf area at V10. What percent yield loss can you expect?
a) 100 b) none c) 5 d) 50 e) 8
14. If you plant 34,000 seeds per acre in 30-inch rows, how many inches apart will seed be spaced?
a) 9.2 b) 6.1 c) 5.5 d) 4.9 e) 12.3
15. This early-season root pest is the toughest to manage with seed-applied insecticides:
a) wireworm b) corn rootworm c) cutworm d) white grub
16. This insect is known for “shot-hole” damage:
a) wireworm b) armyworm c) gypsy moth d) European corn borer
17. Treating corn rootworm adults to reduce egg-laying is cost-effective. True or false?
18. Treat for Japanese beetles if silks are clipped less than a half-inch before pollination is 50% complete and beetles are actively feeding. True or false?
19. Fungicides will help control Goss’s bacterial wilt. True or false?
20. Stunted, spindly plants with light green color could be deficient in sulfur. True or false?
Answers, with page number in the Purdue guide in parenthesis: 1. a (12); 2. c (13); 3. c (15); 4. b (18); 5. a (19-20); 6. c (23); 7. d (25); 8. a (28); 9. c (32); 10. d (55, 213); 11. c (56); 12. d (56); 13. e (61); 14. b (63); 15. a (67); 16. d (74); 17. false (77); 18. true (79); 19. false (92); 20. true (216)
Key: If you got 16 to 20 correct, 300-bushel yields are in your future; 11 to 15 correct, you’re a corn king; 6 to 10 correct, you better buy the 2019 Purdue guide; 0 to 5 correct, did you even try?