Crop Insurance Today Third Quarter 2019 - 13

research, conducted in Manhattan, Kansas,
and Clay Center, Nebraska, builds on prior research in the Central and Eastern Cornbelt. At
Manhattan, researchers evaluated two hybrids
differing in relative maturity by six days and
grown under rainfed and irrigated conditions.
At Clay Center, researchers chose five hybrids
differing in relative maturity and drought tolerance, and included an old hybrid, B73 x Mo17.
The researchers tracked grain fill and weighed
ears weekly from silking until black layer to determine grain fill rates and the weight of ears
at differing stages of maturity. The ear weights
were then used to compute starch (maturity)
line factors for the maturity line weight method. The data from Kansas and Nebraska will
be integrated with the data from previous research (Table 1).

CORNSecond Loss
Minnesota, Illinois, Ohio
Research began in 2018 to continue studying
the effects of second losses on corn. Earlier research looked at defoliation at the 10- and 15-leaf
stages followed by damage at either 15-leaf (first
damage at 10-leaf) or at tassel stage. The current
research is again focused on defoliation at the 10and 15-leaf stages but adds secondary damage at
the reproductive stages of grain fill. The research
was conducted in Minnesota, Illinois, and Ohio
and results are shown in Tables 2, 3, and 4.

GRAIN SORGHUMStand
Reduction
Kansas
A stand reduction trial began in 2017 at locations in Kansas and Texas-the top two states for
grain sorghum production. The trial is evaluating
25, 50, 75, and 90 percent stand reduction at two
plant populations (40,000 and 80,000 seeds/acre),
and at three growth stages: 5-Leaf, Boot, and
Soft Dough. These growth stages coincide with
growing point differentiation, grain head development, and grain filling, respectively. The preliminary results (two years in Kansas; one year in
Texas) indicate that the current stand reduction
chart overestimates losses at the 5-leaf growth
stage for both plant populations (Table 5). Losses
at boot and dough stages shift from the stand reduction chart to a 1-for-1 basis. Loss at boot stage
were considerably less than 1-for-1, and those at
dough stage were also less than 1-for-1, albeit not
as great as those at the boot stage.

A researcher uses a weed eater to "defoliate" peanuts as part of the ongoing study on how plants
recover after damage at different stages of growth.

Table 4 EFFECT OF MULTIPLE DEFOLIATION EVENTS on corn
production in Ohio 2018
Stage(s) of 50% Defoliation
1st Damage
2nd Damage

10-Leaf
15-Leaf
Blister
Milk
Soft Dough
10-Leaf
10-Leaf
10-Leaf
15-Leaf
15-Leaf
15-Leaf

-
-
-
-
-
Blister
Milk
Soft Dough
Blister
Milk
Soft Dough

Appraised

Loss (%)
Measured

Difference

Significantly
Different at 5%

6
15
22
18
12
25
22
16
28
26
22

2
19
32
16
6
22
25
16
27
25
23

-4
4
10
-2
-6
-3
3
0
-1
-1
1

No
Yes
Yes
No
No
No
No
No
No
No
No

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Crop Insurance Today Third Quarter 2019

Table of Contents for the Digital Edition of Crop Insurance Today Third Quarter 2019