Number 293 April 22, 2011

Transcription

1 Number 293 April 22, Fertilization strategies for iron chlorosis in soybeans 1 2. Evaluating the need for fungicides in wheat 4 3. What is Wheat s Up? Wheat Diagnostic School in Garden City May Comparative Vegetation Condition Report: April 5 April Fertilization strategies for iron chlorosis in soybeans During 2009 and 2010, we conducted tests at seven locations in Kansas with seed coating treatments and foliar iron treatments to correct iron deficiency symptoms in soybean. We used two varieties, one with good iron chlorosis tolerance and one that was susceptible to iron chlorosis. The tests were under irrigated conditions. The seed coating treatment was approximately 0.3 lb/acre of actual Fe as chelated EDDHA Fe (6%). The foliar treatments were 0.1 lb/acre EDDHA Fe (6%) and 0.1 lb/acre HEDTA Fe (4.5%). There was an untreated check included. Soil ph at these locations varied from 7.9 to 8.4. Soybean response to seed coating with chelated iron fertilizer. Photos by Dorivar Ruiz Diaz, K-State Research and Extension. 1

2 Greenness. The seed coating treatment had a significant effect in improving the greenness of the foliage, as shown by the chlorophyll meter reading. Overall, the greening response to the seed coating was greater than response to foliar iron applications. The variety most susceptible to iron chlorosis greened up in response to the seed coating much more than the variety more tolerant to iron chlorosis. The tolerant variety stayed greener during the growing season but still showed some additional benefit from the seed coating treatment. The seed treatment also increased plant height by an average of about 5 inches for both varieties (data not shown). 40 Chlorophyll meter readings EDDHA Fe 6% HEDTA Fe 4.5% No foliar c c c ab ab ab b b b a a a 5 0 No Seed Fe With Seed Fe No Seed Fe With Seed Fe Susceptible Variety Tolerant Variety Treatments Chlorophyll meter reading after foliar Fe application. Higher values are correlated with greener plant leaves. Under these conditions favorable to iron chlorosis, an iron chelate seed coating improved greenness readings on both the susceptible and tolerant varieties. The 6% and 4.5% foliar treatments had no effect on greenness. Different letters indicate statically significant differences. Yield. Both the tolerant and susceptible variety also had a good yield response to the iron chelate seed coating, and no significant yield response to the foliar iron chelate treatments. Yield increase due to the seed coating treatment in the susceptible variety was approximately 10 bu/acre, with similar yield increase for the tolerant variety. 2

3 EDDHA Fe 6% HEDTA Fe 4.5% No foliar a ab ab b a ab Yield (bu/acre) c c c c c c No Seed Fe With Seed Fe No Seed Fe With Seed Fe Susceptible Variety Tolerant Variety Treatments Average yield for the tolerant and susceptible varieties and foliar Fe fertilizer. The Fe chelate seed coating had a much larger effect on yields than the 6% or 4.5% foliar treatment on both the susceptible and tolerant varieties. Different letters indicate statically significant differences. Summary * Foliar Fe treatments to soybeans with iron chlorosis seem to increase the greenness, but our results suggest that yield increase may be inconsistent in western Kansas. * An iron chelate seed coating provides significant yield increases to soybeans under conditions with severe iron chlorosis issues. Another alternative to seed coating is in-furrow application of chelated Fe fertilizer, which has shown comparable results. Seed contact with the fertilizer source seems to be particularly important for reducing iron chlorosis symptoms. * If iron chlorosis has been a common problem in the past, producers should select a soybean variety that is tolerant to Fe chlorosis. It may also pay to also use a chelated iron in-furrow application, or an iron chelate seed coating. * Producers should avoid excessive application of nitrogen fertilizer to the crop that precedes soybeans in the rotation. In fields with some risk of iron chlorosis, the high levels of soil nitrate may be a complicating factor. This study is funded by the Kansas Soybean Commission. -- Dorivar Ruiz Diaz, Nutrient Management Specialist ruizdiaz@ksu.edu 3

4 2. Evaluating the need for fungicides in wheat The wheat crop is fast approaching growth stages where fungicide should be applied. Many growers are asking about the potential need for fungicides this year. We have been conducting fungicides evaluations for the past three years in multiple locations in Kansas. Our goals are to (1) help growers evaluate which varieties are most likely to give a favorable yield response to fungicides, and (2) identify situations when these products are most likely to result in a yield response great enough to justify the applications. The locations in included Sumner, Reno, and Republic counties. The treatments included comparisons of fungicide treated and untreated plots of 10 wheat varieties with different levels of genetic resistance to multiple diseases. Which wheat varieties are most likely to give a profitable yield response to foliar fungicides? The wheat varieties in this study were divided into two groups based on their susceptibility to some of the most common leaf diseases in Kansas. The group with multiple susceptibilities included Jagger, Jagalene, 2137, Overley, PostRock, and Fuller. The group of varieties that currently has higher levels of resistance to these same diseases includes Everest, Armour, SantaFe, and Karl 92. The results of this study indicate that the average yield response of the varieties with multiple susceptibilities was at least double that of the more resistant varieties (Figure 1). The chance of a yield response of at least 4 bu/acre (a yield response that is comparable to the average yield response in Kansas, and which results in a reasonable profit for the grower) was much greater when applying fungicides to the varieties with multiple disease vulnerabilities than those with higher levels of resistance (Figure 2). 4

5 Comparison of the yield response of wheat varieties with different levels of susceptibility to the most common leaf diseases to those with resistance. Varieties with a foliar disease index of less than 26 are considered to have genetic resistance to multiple leaf diseases. 5

6 Comparison of the chance of a yield response of wheat varieties with different levels of susceptibility to the most common leaf diseases to those with resistance. Varieties with a foliar disease index of less than 26 are considered to have genetic resistance to multiple leaf diseases. Can scouting for disease improve my chances of seeing a yield increase when using fungicide applications? The results of this study indicate that taking the time to scout for disease can greatly increase chances of correctly identifying situations when it is beneficial to use fungicides in wheat. For example, the average yield response to a fungicide applied to a susceptible variety when the disease is present on the upper leaves at heading was more than 7 bu/acre (Figure 3). The average yield response for the same variety when no disease is observed at heading is about 1.5 bu/acre. The average yield response when spraying a variety with higher levels of genetic resistance is about 0.3 bu/acre. The same patterns carry through when we consider the chances of seeing a 4 bu/a yield response (Figure 4). 6

7 Comparison of yield response resulting from a fungicide application to wheat at various local disease risk levels. Local risk: Low = No disease present at heading and no reports of rust in Kansas, Oklahoma, or Texas. Moderate = Disease present in the lower canopy at heading, reports of rust in Kansas, Texas, and Oklahoma. High = Disease present on top two leaves at heading. 7

8 Comparison of chance of yield response resulting from a fungicide application to wheat at various local disease risk levels. Local risk: Low = No disease present at heading and no reports of rust in Kansas, Oklahoma, or Texas. Moderate = Disease present in the lower canopy at heading, reports of rust in Kansas, Texas, and Oklahoma. High = Disease present on top two leaves at heading. The higher prices of grain and lower cost of some fungicide products make even small yield improvement a reasonable investment. Growers can use the average yield responses from this study to help evaluate how aggressive they want to be with fungicides this year. Key concepts for profitable use of fungicides: - Wheat varieties that are susceptible to the most common leaf diseases are more likely to give and larger and more consistent yield response to foliar fungicides than varieties with resistance to these diseases. - Paying attention to the regional risk of disease and scouting your fields greatly increases your chances of identifing years where fungicides result in the largest yield responses. The current risk of disease is low in most areas of the state. There have been a few reports of low levels of leaf rust and powdery mildew in central Kansas, suggesting some fields might be at a moderate risk of disease. The dry weather is probably slowing the spread of disease. The lower cost of fungicides and the higher grain prices may still justify treatment. -- Erick DeWolf, Research and Extension Plant Pathology dewolf1@ksu.edu 8

9 3. What is Wheat s Up? This spring as producers travel by their local county wheat plots, they will likely see a Wheat s Up sign posted near the wheat varieties. A Wheat s Up sign indicates that the wheat variety plot is part of a statewide program to educate producers and the agriculture industry on four major components of wheat production. These components are: * Weed control * Disease management * Nutrient management * Crop residue management Each component plays an important part in the development and success of the wheat crop, or the subsequent crop after wheat. K-State Research and Extension agronomists and plant pathologists, along with local agriculture and natural resource agents, have worked together to develop several presentations covering the four major components of production. Producers are highly encouraged to attend the wheat plot tours. One or more of these components will be presented at each of the Wheat s Up wheat tours. The weed component will help wheat producers identify weeds in wheat and provide information that will help them practice cost-effective and environmentally sound weed management. It will also help producers understand the benefits and effectiveness of integrated weed management programs, which leads to maximum profitability. The wheat disease component of the program will help wheat producers better identify which diseases threaten the productivity of their farms, and understand a decision-making process that will help them maximize profitability by using fungicides where needed and avoiding unnecessary pesticide applications. The nutrient management component of the program will increase wheat producers knowledge and understanding of the value of soil sampling, as well as macro and micro nutrient management practices. This understanding can lead to more efficient use of nutrients and soil amendments, and increased yields. The crop residue management component will help participants gain knowledge and a better understanding of the value of residue and stubble height for subsequent crops grown in cropping systems. This can lead to lower production costs, increased water use efficiency, and increased crop yields. In the end, the goal of the Wheat s Up program is to provide the producer with important information about ways to improve production. -- Brian Olson, Northwest Area Crops and Soils Specialist bolson@ksu.edu -- Curtis Thompson, Weed Management Specialist cthompso@ksu.edu -- Jim Shroyer, Extension Agronomy State Leader jshroyer@ksu.edu 9

10 Wheat Diagnostic School in Garden City May Wheat producers and agricultural professionals can learn the latest in wheat management and technology at the 2011 Wheat Diagnostic School. Attendees can also earn up to 10 certified crop advisor credits, four commercial pesticide applicator credits in agricultural plant pest control and a core hour for commercial pesticide applicators. K-State Research and Extension agents, professors, and specialists from a variety of fields will speak at the conference, which will cover topics such as GMO wheat, herbicide performance, nutrients, GPS, fungicides, and more. The conference will be held from May 11 to 12 at the K-State Southwest Research-Extension Center at 4500 E. Mary St. Early bird registration is due May 4, with a fee of $75. Registration at the door will be $100. Fees include informational materials, lunch, and beverages. For more information, contact Kent Martin or Lynn Harshbarger at or kentlm@ksu.edu. -- Kent Martin, Southwest Area Crops and Soils Specialist kentlm@ksu.edu 5. Comparative Vegetation Condition Report: April 5 April 18 K-State s Ecology and Agriculture Spatial Analysis Laboratory (EASAL) produces weekly Vegetation Condition Report maps. These maps can be a valuable tool for making crop selection and marketing decisions. Two short videos of Dr. Kevin Price explaining the development of these maps can be viewed on YouTube at: The objective of these reports is to provide users with a means of assessing the relative condition of crops and grassland. The maps can be used to assess current plant growth rates, as well as comparisons to the previous year and relative to the 21-year average. The report is used by individual farmers and ranchers, the commodities market, and political leaders for assessing factors such as production potential and drought impact across their state. The maps below show the current vegetation conditions in Kansas, the Corn Belt, and the continental U.S, with comments from Mary Knapp, state climatologist: 10

11 Map 1. The Vegetation Condition Report for Kansas for April 5 18 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the continuation of cool temperatures and dry soils have allowed for little photosynthetically active biomass production, particularly in the western third of the state. Northwest Kansas experienced snow during the middle of the period, but little moisture from the event. 11

12 Map 2. Compared to the 22-year average at this time for Kansas, this year s Vegetation Condition Report for April 5 18 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows below-normal photosynthetically active vegetative production in areas of western Kansas. The lower-than-normal photosynthetic activity is also pronounced in the western parts of southeast Kansas. Cowley, Chautauqua, and Elk counties in particular missed rains that favored the eastern counties, such as Cherokee and Crawford. 12

13 Map 3. The Vegetation Condition Report for the Corn Belt for April 5 18 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the most active photosynthetic production is occurring in the southern areas of the region, particularly central Kansas, southwestern Missouri, and western Kentucky. Much of North and South Dakota, Iowa, Illinois, and Indiana report excessively wet crop moisture indices. 13

14 Map 4. Compared to the 22-year average at this time for the Corn Belt, this year s Vegetation Condition Report for April 5 18 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows Eastern Minnesota into Michigan are experiencing greater-than-average photosynthetically active biomass production. North Dakota is experiencing below-normal photosynthetically active biomass production, as flooding continues. In western Kansas, the lack of activity is due more to the drier-than-normal conditions. West central into southwest Kansas continue to experience moderate to severe drought. 14

15 Map 5. The Vegetation Condition Report for the U.S. for April 5 18 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows greater photosynthetically active biomass production in the South, and northward into Kentucky and Virginia. The Upper Plains region is slow to develop photosynthetically active vegetative production due to cool temperatures and saturated soils. From western Kansas south to Texas, the dry conditions are slowing the development of photosynthetically active vegetative production. 15

16 Map 6. The U.S. comparison to the 22-year average for the period April 5 18 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows most of the country is ahead of average in terms of photosynthetically active vegetative production. There are exceptions, most noticeably in North Dakota, where saturated soils continue to slow development. The other noticeable exception is the southern Plains region, where drought conditions continue to delay photosynthetically active vegetative development. Note to readers: The maps above represent a subset of the maps available from the EASAL group. If you d like digital copies of the entire map series please contact us at kpprice@ksu.edu and we can place you on our list to receive the entire dataset each week as they are produced. The maps are normally first available on Wednesday of each week, unless there is a delay in the posting of the data by EROS Data Center where we obtain the raw data used to make the maps. These maps are provided for free as a service of the Department of Agronomy and K-State Research and Extension. -- Mary Knapp, State Climatologist mknapp@ksu.edu -- Kevin Price, Agronomy and Geography, Remote Sensing, Natural Resources, GIS kpprice@ksu.edu -- Nan An, Graduate Research Assistant, Ecology & Agriculture Spatial Analysis Laboratory (EASAL) nanan@ksu.edu These e-updates are a regular weekly item from K-State Extension Agronomy and Steve Watson, Agronomy e-update Editor. All of the Research and Extension faculty in Agronomy will be involved as sources from time to time. If you have any questions or suggestions for topics you'd like to have us address in this weekly update, contact Steve Watson, swatson@ksu.edu, or Jim Shroyer, Research and Extension Crop Production Specialist and State Extension Agronomy Leader jshroyer@ksu.edu 16