aphid_day_calculator_test_2019 (2)

	C	D	E	F	G	H	I	J	K	L	M
1	FOR DEMONSTRATION PURPOSES ONLY
2	Aphid day calculator
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5	ENTER	Doubling time in days				3
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7	ENTER	Starting population/plant				250
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9	ENTER	Starting Cumulative Aphid Days				1100
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14	DAY	0	3	6	9	12	15	18	21	24	27
15	aphids /plant	25	50	100	200	400	800	1,600	3,200	6,400	12,800
16	cumulative aphid days	1,100	1,213	1,438	1,888	2,788	4,588	8,188	15,388	29,788	58,588
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20	Very large soybean aphid poplations can affect yield until R6.5 ( a yellow pod on on plant)
21	Typically at 250 aphids/plant 500-1100 aphid -days would have accumulated (CAD)*
22	*Economic injury can occur from 5,000 or more cumulative aphid days on R4 or younger growth stages and with growing season stress.
23	*Later growth stages and good growing conditions will require more aphid days to significantly impact yield.
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25	This spreadsheet does not adjust for crop stage and other factors affecting doubling times
26	Probability of yield loss from as ET soybean aphid population decreases as soybean growth stage increases. (R3 > R4> R5 > R6)
27	Soybean aphids reproduction most rapid R2-R4 and Late R5-early R6					Under ideal environmental conditions, soybean aphid populations can double every 2 days (usually 3 days or longer).
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30	Soybean stage				Average days*		Late planting, early maturity group and stress can reduce some of these intervals,
31	R1 - R3	Beginning -Begin Pod			10
32	R3-R4	Begin Pod - full pod			9
33	R4-R5	Full Pod - begin seed			9
34	R5-R6	Begin seed - full seed			15
35	R6-R7	Full seed - Begin maturity			18
36	Source:	Hardman and Gusolus. 1991. Soybean growth and development & management Information for replant decsions. Minnesota Extension Service
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