Understanding Stalk Lodging Better  11/20/17 10:05:04 AM

HAPPY THANKSGIVING!!!  We again THANK YOU for your continued patronage.  We hope that you are able to take time this week and give thanks for the many blessings we all share on a daily basis. 

Year in Review—All and all, the crops in these parts was very respectable given everything that took place.  Remember these things—Mid April cold rains that slowed or stopped corn planting for some.  A slow emerging corn stand, uneven stand establishment for corn and soybeans, Japanese beetles, struggles with weed control, Southern rust and late emerging Gray Leaf Spot in corn, “cool drought in August”, 6-8” of rain in early October followed by 3 days of un-believable winds in late October.    When you think of these things, as well as other factors, it is hard to believe that we raised the crop that we did.  However, it is a testament to the planning, hard work, and patience it takes to annually raise a crop. 

Corn stalk lodging--What was the cause?  Easy—3-4 days of 40+ mph winds!  Yes, this was certainly a big part of it.  But, other factors such as: 1) lower fertility levels of certain areas of the fields likely had more lodging than others 2) soil compaction—high traffic areas or areas where root growth has/was restricted throughout the season, likely saw more lodging, 3) Genetics—certainly played a role as far as stalk strength and late season plant health 4) Was a fungicide used?  It was not in-fallible that ALL corn treated with a fungicide stood perfectly—BUT those treated fields stood better and yielded better than those without the fungicide treatment   5) 6-8 inches of rain in early October—Many field were likely pre-disposed to some form of stalk weakness prior to the rains early in October.  The rains made it worse.  The moisture amplified the level and rate of continuing infection and stalk degradation.  6) NOW THE WIND—The wind was the final ingredient that made this harvest struggle complete.

So, what can we learn……All of the for-mentioned factors and likely a few others played a role in the final out-come.  Was one more important than the other?  That will certainly be argued all winter.  If the wind had not come up, we might not even be having this conversation.  However, let’s understand a couple of additional things we have not mentioned, as to what within the corn plant can cause certain fields to be pre-disposed to stalk lodging.

Stalk Cannibalization

Pollination and grain fill put tremendous demands on corn plant and if there was a lack of rainfall, fertility for the developing yield, or restriction of root development, this caused corn plants to cannibalize stalks to feed kernels. Stalk cannibalization causes disintegration of pith cells and impacts the amount lignin in cell walls of the rind. This leads to physiological stalk lodging, also referred to as stress lodging during dry years.

 

Physiological Stalk Lodging

Physiological stalk lodging occurs when not enough lignin is deposited in rind of the stalk during grain fill. Lignin is made up of a complex of sugar molecules, binds cellulose fibers together, and ‘cements’ corn tissues.  Often the bowing of stalks prior to physiological maturity (black layer) is an early indicator that lignin is not being formed well enough to support some plants.  One key feature of physiological stalk lodging is it occurs without any evidence of stalk rot pathogens, meaning the pith remains white and healthy.

 

Both of these issues have a ripple affect—if the stalk is cannibalizing and lacking lignin at the lower nodes of the stalk, does it make the stalk more susceptible to ill-affects of everything we have already mentioned?  YES!!

Did you notice any pattern as to where the stalks lodged?  Was it the 2-3 nodes above the soil line? 

Yes, high ear placement and taller plants also play roles here—it can be a matter of physics—the taller the plant, the higher the ear placement, the more leverage the wind would have to blow it over.  However, remember that the oldest areas of the corn plant—the lower nodes of the stalk can also serve a nutrient source to the rest of the plant.  If the plant can’t get the nutrition demands that the developing ears need from the roots system, the plant can and will pull nutrition and water from the lower areas of the stalk in order to fill out the kernels of the ear, thus, making the lower area of the stalks weaker, and more prone for added ill-affects of disease, wind, etc. 

What can you change?  Certainly, a few things can be gleaned off of this fall as product of the wind events—1) Fields with higher fertility levels seemed to fare better.  2) Foliar Fungicides were worth every penny—it sometimes takes events like this to see the added value foliar fungicide applications bring to your acre beyond the extra yield.  If you can’t get it in the corn head, it is harder to achieve higher yields.  3)  Planting dates, hybrid selection, hybrid harvest order and late season plant health all matter. 

 

Replace what you Harvest! Redundant topic, but necessary to think about..  We just harvested another big crop.  If you think about it, we have been on a bit of a production role for the last few years.  WE had this same discussion last year at this time!!  I know that spending money on fertilizer for next year may not be on the top of your considerations right now. However, now is the time to soil sample and begin the planning process for next season.  How much fertility did you really remove from the soil with the crop you just harvested?  I will again refer to the following table.  We have used it for years and although some may argue certain element recommendations, this is a good base resource when thinking about how much fertility you just harvested in the grain and stover.  It is also posted on our website under Crop Nutrient Removal Guides. 

 

 

 

 

 

 

 

 

 

 

Nutrient Removal Chart describing how much of each type of nutrient is removed by a soybean crop.

 

 

 

 

 

 

 

 

 

 

 

 

Bushels/Acre

 

90

85

80

75

70

65

60

55

50

45

40

 

Used for

 

 

 

 

 

 

 

 

 

 

 

Nitrogen (N)

Grain

342

323

304

285

266

247

228

209

190

171

152

 

Stover

99

93.5

88

82.5

77

71.5

66

60.5

55

49.5

44

 

Total Use

441

416.5

392

367.5

343

318.5

294

269.5

245

220.5

196

Phosphate (P2O5)

Grain

76.5

72.25

68

63.75

59.5

55.25

51

46.75

42.5

38.25

34

 

Stover

22.5

21.25

20

18.75

17.5

16.25

15

13.75

12.5

11.25

10

 

Total Use

99

93.5

88

82.5

77

71.5

66

60.5

55

49.5

44

Potassium (K2O)

Grain

117

110.5

104

97.5

91

84.5

78

71.5

65

58.5

52

 

Stover

90

85

80

75

70

65

60

55

50

45

40

 

Total Use

207

195.5

184

172.5

161

149.5

138

126.5

115

103.5

92

Sulfur (S)

Grain

16.2

15.3

14.4

13.5

12.6

11.7

10.8

9.9

9

8.1

7.2

 

Stover

15.3

14.45

13.6

12.75

11.9

11.05

10.2

9.35

8.5

7.65

6.8

 

Total Use

31.5

29.75

28

26.25

24.5

22.75

21

19.25

17.5

15.75

14

Zinc (Zn)

Grain

0.090

0.085

0.080

0.075

0.070

0.065

0.060

0.055

0.050

0.045

0.040

 

Stover

0.30

0.28

0.27

0.25

0.23

0.22

0.20

0.18

0.17

0.15

0.13

 

Total Use

0.39

0.37

0.35

0.32

0.30

0.28

0.26

0.24

0.22

0.19

0.17

 

 

 

 

 

 

 

 

 

 

 

 

 

Nutrient Removal Chart describing how much of each type of nutrient is removed by a corn crop.

Bushels/Acre

 

300

280

260

240

220

200

180

160

140

120

100

 

Used for

 

 

 

 

 

 

 

 

 

 

 

Nitrogen (N)

Grain

270

252

234

216

198

180

162

144

126

108

90

 

Stover

135

126

117

108

99

90

81

72

63

54

45

 

Total Use

405

378

351

324

297

270

243

216

189

162

135

Phosphate (P2O5)

Grain

114

106.4

98.8

91.2

83.6

76

68.4

60.8

53.2

45.6

38

 

Stover

48

44.8

41.6

38.4

35.2

32

28.8

25.6

22.4

19.2

16

 

Total Use

162

151.2

140.4

129.6

118.8

108

97.2

86.4

75.6

64.8

54

Potassium (K2O)

Grain

81

75.6

70.2

64.8

59.4

54

48.6

43.2

37.8

32.4

27

 

Stover

330

308

286

264

242

220

198

176

154

132

110

 

Total Use

411

383.6

356.2

328.8

301.4

274

246.6

219.2

191.8

164.4

137

Sulfur (S)

Grain

24

22.4

20.8

19.2

17.6

16

14.4

12.8

11.2

9.6

8

 

Stover

21

19.6

18.2

16.8

15.4

14

12.6

11.2

9.8

8.4

7

 

Total Use

45

42

39

36

33

30

27

24

21

18

15

Zinc (Zn)

Grain

0.300

0.280

0.260

0.240

0.220

0.200

0.180

0.160

0.140

0.120

0.100

 

Stover

0.55

0.51

0.48

0.44

0.40

0.37

0.33

0.29

0.26

0.22

0.18

 

Total Use

0.85

0.79

0.74

0.68

0.62

0.57

0.51

0.45

0.40

0.34

0.28

 

 

Thinking of skipping?  Yes commodity prices are lower than what anyone would like, and, skipping or reducing applications of P and K out of the N, P, K, mix might not be as detrimental as reducing nitrogen (N), it can still impact yield potential and stress tolerance.

 

 

 

Phosphorus

Uptake of P increases rapidly after about the V6 growth stage, approximately 4 to 6 weeks after corn planting. Uptake continues until near

maturity. Plants that are phosphorus deficient typically have a purple or dark green color because leaf expansion is retarded more than chlorophyll and

chloroplast formation. Plants grow slowly, stalks are thin and shortened, and maturity is usually de-layed. Other factors that may cause

purple corn include the following: cold temperatures, wet soils, compaction, and root injury. Soil testing can reveal if P is deficient.

Unlike nitrogen, P has a relatively short range of movement in the soil and is therefore considered an “immobile nutrient.” P requires moist

soil for effective root uptake. As a result, dry soil conditions can negatively affect soil uptake by corn roots.

Role of P. Skipping or reducing fertilizer applications for one year may have minimal impact on yield potential in many cases, due to the“banked” levels of P. However, having less available P can impact the plant in other ways, especially under stressful conditions. Basically, P is the main nutrient responsible for energy production in the plant. Without enough P to properly support energy production, corn cannot grow, produce, or handle stress as it should. It sounds simple, but it is absolutely critical to a successful crop.

Management. Soil fertility level for P is greatly impacted by the inherent availability in the soil and crop removal. Each bushel of corn harvested

per acre removes approximately 0.4 pounds per acre of P2O5. Each bushel of soybeans harvested per acre removes approximately 0.85 pounds per acre of P2O5. Soil tests are recommended every 4 years or less. If there is concern about fertility, especially due to very high or very low yields , take

soil tests to aid with fertility decisions.

 

Potassium

Uptake of K. Potassium uptake increases rapidly after about the V6 growth stage, approximately 4 to 6 weeks after corn planting. Therefore, when K demand becomes large and there is not enough available K, plant deficiency symptoms become visible.   Uptake of potassium is completed soon after silking (R1stage). Potassium deficiency is characterized by yellow and brown margins beginning at the leaf tips and can often be confused with nitrogen deficiency. Like nitrogen, potassium is mobile in the plant so lower leaves are affected first. Potassium deficiency is favored by low soil test K, compaction, and conservation tillage where no subsurface band of K is used. Dry soil conditions can also negatively affect soil uptake by corn roots.

Role of K. Potassium is one of 12 nutrient elements required for normal corn growth and development. Specifically, K has been linked to improved

stalk strength. When corn takes up sufficient K, stalk drydown is slowed after maturity. Thus, the risk of lodging after maturity may be reduced if K levels are adequate for crop production.

Management. Similar to P, soil fertility level for K is greatly impacted by the inherent availability in the soil and crop removal. Each bushel of corn harvested per acre removes approximately 0.29 pounds per acre of K2O, and each bushel of soybeans harvested per acre removes approximately 1.45 pounds per acre of K2O. As previously suggested for P, basing fertilizer applications on soil tests and residual fertility is also recommended for K.

In Summary, as yield potential continues to increase, it is critical to manage soil fertility. While reducing fertilizer inputs may decrease your costs, it may not improve your bottom line. Please carefully consider the risks of reducing fertilizer inputs on crop production.

 
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