Number 295 May 6, 2011

Transcription

1 Number 295 May 6, Summer cover crops in a no-till wheat/grain sorghum rotation 1 2. The role of management in soil compactability and ability to handle traffic 3 3. Evaluating corn stands and early-season growth 5 4. False chinch bug found in winter canola Wheat disease update: Stripe rust, leaf rust, viral diseases Wheat Field Day, May Comparative Vegetation Condition Report: April 19 May April climate summary for Kansas Summer cover crops in a no-till wheat/grain sorghum rotation Between wheat harvest and grain sorghum planting, there is plenty of opportunity to grow either a winter or a summer cover crop. At the former Harvey County Experiment Field near Hesston, both of those options have been tested on a Geary silt loam soil by Mark Claassen, professor emeritus and former agronomist-in-charge at the field. Research over an 8-year period, ending in 2001, explored the use of hairy vetch as a winter cover crop following wheat in a winter wheat-sorghum rotation. Results showed that between September and May, hairy vetch can produce a large amount of dry matter with an N content of approximately 100 lb/acre. However, using hairy vetch as a cover crop also has significant disadvantages, including cost and availability of seed, interference with control of volunteer wheat and winter annual weeds, and the possibility of hairy vetch becoming a weed in wheat after sorghum. Then from 2002 through 2008, wheat and grain sorghum were grown in three no-till crop rotations at two adjacent sites. Two of the rotations included a summer cover crop -- either a latematuring Roundup Ready soybean (Asgrow AG7601 was used in 2008) or sunn hemp -- established following wheat harvest. Nitrogen (N) fertilizer was applied to both the grain sorghum and wheat at rates of 0, 30, 60, and 90 lb/acre. Wheat was planted as soon as practicable following grain sorghum harvest. 1

2 In 6 site-years, soybean and sunn hemp produced dry matter yields of 2.42 and 3.43 ton/acre with N yields of 111 and 134 lb/acre, respectively. Both cover crops had a positive impact on grain sorghum yield, particularly at N rates of 60 lb/acre or less. The soybean effect was masked with 90 lb/acre of N. Over the long term, however, sunn hemp tended to show a sorghum yield benefit even at the highest N rate. Averaged over N rates, soybean and sunn hemp resulted in 6- year average grain sorghum yield increases of 8.8 and 14.9 bu/acre, respectively. Positive residual effects of soybean and sunn hemp on the yield of wheat after sorghum were small and mostly observed at N rates of 60 lb/acre or less. Five-year mean wheat yields combined from the two sites and averaged over N rate indicated numeric increases of 2.2 and 2.9 bu/acre in rotations with soybean and sunn hemp vs. no cover crop. Grain sorghum yields Effect of soybean and sunn hemp cover crops and N rate on no-till grain sorghum after wheat: Harvey County Experiment Field Cover crop N rate (lb/acre) Grain sorghum yield (6-year average) None Soybean Sunn hemp Mean effect of cover crops on grain sorghum yield Cover crop Mean grain sorghum yield (6-year average) None 83.7 Soybean 92.5 Sunn hemp 98.6 Mean effect of N rate on grain sorghum yield N rate (lb/acre) Mean grain sorghum yield (6-year average)

3 Wheat yields Effect of soybean and sunn hemp cover crops and N rate on no-till wheat after grain sorghum: Harvey County Experiment Field Cover crop N rate (lb/acre) Wheat yield (5-year average) None Soybean Sunn hemp Mean effect of cover crops on wheat yield Cover crop Mean wheat yield (5-year average) None 23.1 Soybean 25.3 Sunn hemp 26.0 Mean effect of N rate on wheat yield N rate (lb/acre) Mean wheat yield (5-year average) For a discussion of how the cover crops in this long-term research affected soil quality, see Agronomy e-update No. 283, Feb. 11, 2011, at: For complete details of this study, see K-State Research and Extension publication SRP-1048, Field Research 2011, at: -- Steve Watson, Agronomy e-update Editor swatson@ksu.edu 2. The role of management in soil compactability and ability to handle traffic Conducting field work -- including tillage, planting, or traffic in general -- after wet weather can cause soil compaction, and in particular sidewall compaction in the seed furrow. The worst cases of sidewall compaction are seen after a field has been planted when the soil was too wet, followed by a period of dry weather. If the soil stays moist, the roots are usually able to grow through the walls of the seed furrow. But if the soil gets dry, the roots can have a harder time growing through that seed furrow wall, and instead grow along the furrow, resulting in what is referred to as sidewall compaction. 3

4 With corn, the plants might look fine for a while, but the symptoms of this problem will probably show up after the plants get to be several inches tall. Symptoms will look like drought stress, nutrient deficiency, or both. Since there aren t any good ways to fix sidewall compaction once it exists, the best practice would be to avoid creating the problem in the first place. This means waiting until soils are dry enough to plant. The way to test for this is to dig down to the desired planting depth, and try to make a ball with the soil. Next, see if the ball will crumble or crack apart, or if it deforms like molding putty. If it crumbles, it s ready to plant. If it deforms, it would be best to wait before resuming field operations. Even waiting as little as half a day could make a big difference. Soil management also has an effect on the how well soils can handle traffic under various moisture conditions. Recent research from western Kansas/eastern Colorado/western Nebraska shows that no-till soils are less compactable in general than conventional or reduced-tillage soils. This is partially because no-till increases soil organic matter (SOM) levels, which in turn will increase soil aggregation and improve soil structure. Increases in SOM also lead to improvements in the compactability of soil, because SOM is elastic and absorbs water. The graphs in Figure 1 show that at each of four research locations in the High Plains, the no-till treatment had the lowest bulk density (as shown by the lowest line on each of the graphs). Also, at all locations, the line for the no-till treatment is shifted to the right, which means that at equal compactive forces, the plowed soils became compacted at lower water contents, and that the notill soils required higher water contents before becoming compacted. Practically speaking, this means that: * Tilled soils are more easily compacted, and that plowed soils become compacted at lower water contents than no-till soils. * No-till soils can be trafficked at relatively higher water contents and have less susceptibility to compaction than tilled soils at the same water content. 4

5 Source: Blanco et al., 2009, SSSAJ, Vol. 72, No DeAnn Presley, Soil Management Specialist deann@ksu.edu 3. Evaluating corn stands and early-season growth Getting a good stand of corn, with vigorous early-season growth, is the first step in getting good yields. When adverse conditions, such as a hard rain or unusually cool weather, occur after planting and emergence, producers should get out in their fields and take a close look at how their corn is doing. This year, much of the early-planted corn has been slow to emerge or has grown slowly if it emerged before the cool temperatures of the past couple of weeks. Now is a good time to check fields planted in mid-april that have not yet emerged, or are just starting to emerge. Research has shown that a 25 percent loss of stand at emergence results in less than 10 percent yield loss. Replanting may not be necessary if the remaining stand is relatively uniform (few large gaps in adjoining rows) and is within 20 percent of the target population. 5

6 Don t give up on a stand too easily, but if you decide the stand is inadequate, replanting should be done as soon as possible to provide the best chance to maximizing yields. Corn germination and emergence Before examining their fields, producers should first understand how corn emergence and germination should be progressing under ideal conditions. This is, in fact, what happens in the vast majority of cases, at least in Kansas. A medium-maturity hybrid requires roughly 120 Growing Degree Units (GDUs) to emerge. Planting depth and soil moisture can modify actual time to emergence, but if more than 120 GDU have been accumulated with no emergence, it may be time to start digging up seed to see what is going on. Germination is the time when the radicle, or seed root, breaks through the seed coat. However, before that happens, the seed must soak up enough water to initiate enzyme activity and cell growth. The coleoptile is the next structure to elongate and break through the seed coat. This leaf-like structure encloses the embryonic leaves, protecting them as they push through the soil before emergence. The last structures to appear are the lateral seminal roots, 3 to 4 seed roots that emerge from the same end of the seed as the coleoptile, and together with the radicle, make up the seminal root system. This root system is the primary source of water and nutrients until the nodal root system takes over at V3 to V5. Soil Surface Coleoptile Crown Mesocotyl Radicle Lateral Seminal Roots Photo by Kraig Roozeboom, K-State Research and Extension. Emergence occurs when the coleoptile breaks through the soil surface. This is accomplished by elongation of the coleoptile and by elongation of the mesocotyl, the root-like structure that connects the crown (base of the stem) and the seed. When the coleoptile senses light, mesocotyl elongation stops, and the depth of the crown is set. 6

7 After emergence, vegetative stages are designated by counting leaf collars. A V1 plant has one leaf collar emerged; a V2 plant has two, and so on. Soon after emergence, at about V1, the nodal root system begins to grow. The first four nodes stay compressed at the base of the stem and give rise to the first sets of nodal roots. By V6 these roots have become the major supplier of water and nutrients to the corn plant and also are important for anchoring the plant to prevent lodging. Nodal roots eventually are initiated from up to 7 to 10 nodes, including several above-ground nodes. First leaf First leaf collar Coleoptile Nodal root Photo by K-State Research and Extension. The growing point typically stays below the soil surface until appearance of the fifth leaf collar. This is important when considering the implications of early-season leaf loss due to a freeze, insect damage, or hail. Don t assume a young corn plant is dead just because the above-ground leaf area is destroyed or severely damaged. Often, if the growing point survives, additional leaves soon emerge and yield losses can be minimal, especially if leaf loss occurs soon after emergence. At about V5 to V6, the growing point differentiates into the tassel. All leaves have been initiated. Although the growing point is above the soil surface by V6 and becomes more vulnerable to above-ground threats, the tightly wound leaf sheaths provide significant protection. Emergence problems Sometimes the corn does not emerge, or does not emerge uniformly. The question then becomes why, and will conditions improve with time? If there is poor seedling emergence, start by looking for patterns. Are emergence problems occurring in small but regular skips across the field, uniformly throughout the field, only in localized areas, or in random scattered area?. Here are just a few of the possible scenarios: 7

8 If emergence problems are relatively uniform throughout the field, you may find that soil surface crusting from a hard rain after planting has prevented emergence. This can be easily verified by a little digging. If seedlings cannot push through the soil surface crust, you should find malformed seedlings just beneath the soil surface. A uniform pattern of skips suggests a clogged, jammed, or broken planter. Uneven patterns of emergence may be caused by prolonged waterlogging in low-lying areas of the field. Poor emergence or uneven emergence can result from planting corn too shallowly, and not having all the seed planted into adequate moisture for germination. Planting too deeply can also result in poor emergence and stand establishment, especially if soils are crusted. Corn seed planted too deeply. The coleoptile could not emerge through the soil surface. Surface compaction was also a problem in this case. Photo by Stu Duncan, K-State Research and Extension. Rodents can also cause patchy stands. If this is the case, there will usually be holes or other obvious evidence of their presence. In the past, wireworms and other soil insects could cause emergence problems, but most corn seed is now treated with an insecticide seed treatment or should be. Early-season growth problems If the plants emerged in good fashion, but the seedlings then have problems maintaining adequate growth and development or leaf color, there may be several possible reasons. A few of the most likely causes include: Unusually cool temperatures, compacted soil, or waterlogging. Wet soils and unusually cool temperatures can inhibit root growth especially, slowing plant development. This can cause yellowed, wilting plants due to poor root growth, drowning, or a seedling blight infection. Seedling blight is often characterized by stem tissue near ground level that is discolored or water-soaked in appearance. Also, planting in wet soil can compact the seed furrow, inhibiting root growth. A shallow compaction layer can slow early root growth, resulting in stunted, nutrient deficient plants. 8

9 Sidewall and seed zone compaction in heavy clay soil. Photo by Stu Duncan, K-State Research and Extension. Early-season lodging. This is usually associated with hot, dry weather during V1 to V6, which prevents adequate development and penetration of nodal roots. Plants can survive for a time on just the seminal root system, but they will have little mechanical support. Reasons for poor nodal root development and an elevated crown include sidewall compaction, erosion after emergence but before nodal root development, and sinking of the seedbed due to pounding rains. Often a good soaking rain is enough to allow nodal roots to establish and plants to recover. Inter-row cultivation can be used to push soil against plants with exposed crowns. Corn seedling lodging caused by shallow planting and poor nodal root development. Photo by Doug Shoup, K-State Research and Extension. White grubs or wireworms. These soil insects may be eating the roots, which will cause the plants to wilt. Black cutworms. These insects, which can be found in the soil or on the surface, cause window paning of the leaves on young plants. Cutworms may also cut off seedling plants at the soil surface. Flea beetles. These tiny leaf-chewing insects can cause scratches on leaves. Eventually, the leaves may shrivel, turn gray, and die. Plants are more susceptible to flea beetle injury when temperatures are cold and seedling growth is slow. Seedling plants are often able to recover from flea beetle injury because the growing point remains below ground level until the fifth leaf emerges. 9

10 Chilling injury (cold weather crown rot). When this occurs, plants are stunted and may display nutrient deficiency symptoms. Root development is usually normal, but the crown will have dark brown or black discoloration, which can be seen by splitting the stem. This kind of injury is associated with unusually cool temperatures from emergence to V4 not freezing, but close to it. Symptoms are similar to Stewart s Wilt, so check for flea beetle feeding, which is the vector for this disease. Freezing temperatures. A freeze that occurs after emergence can cause leaves to first appear watersoaked, then turn white within a few days. A freeze can kill leaves. Plants will recover from this if the freeze occurs before the fifth leaf emerges because the growing point is still underground. Plant roots are undamaged by a freeze. If the weather warms back up sufficiently after the freeze injury occurs, chances of plant survival are increased. If it stays unusually cool and wet, crown rot can occur. In rare cases, such as the Easter freeze of 2007, temperatures can get low enough to damage the crowns below the soil and kill the plants. Corn after a hard freeze caused 25% stand loss in this case. Photo by Stu Duncan, K-State Research and Extension. Free ammonia from an anhydrous ammonia application. This can injure roots and kill germinating seed if the ammonia was applied too shallowly (especially in coarser soils), too close to the time of planting, or if dry soil conditions slowed the conversion of ammonia to ammonium. One way to minimize damage is to apply the ammonia at a 10 to 15 degree angle from the direction of planting. If injury occurs then it is more randomly distributed, reducing the multi-plant skips, and allowing the unaffected plants to compensate. Ammonia injury can also occur when sidedressing anhydrous ammonia under dry soil conditions. Root injury can occur if the plants get too big or the knives run too close to the row. Ammonia injury resulting from poor soil sealing can cause leaves to appear watersoaked or have dead margins. Roots may appear sheared off, or burned off. Plants will normally recover from this injury, but yields can be reduced. Putting a urea-based N fertilizer in contact with the seed. Urea will hydrolyze into ammonia and injure the seedling. 10

11 Seedlings damaged after starter fertilizer containing urea-n was placed in direct seed contact. Photos by Dorivar Ruiz Diaz, K-State Research and Extension. Nitrogen (N) deficiency. This does not usually occur until a later stage of growth in conventional tillage systems. But in no-till corn, especially in high residue situations, N deficiency is common where producers haven t applied nitrogen as a starter, or broadcast a significant amount of N prior to or at planting. In early planting in very cold soils where no N was applied close to the seed as a starter, seedlings may be N deficient in conventional-till also. Nitrogen deficient corn seedlings will be spindly, with pale yellowgreen foliage. As the plants grow, the lower leaves will fire, with yellowing starting from the tip of the leaf and progressing back toward the stalk. Phosphorus deficiency. This can result in stunted growth and purple leaves early in the growing season. Phosphorus deficiency is often enhanced by cool, wet growing conditions. Iron deficiency. This can cause upper leaves to be pale green between the veins. Iron deficiency is more common on high ph and calcareous soils. Sulfur deficiency. This can result in stunted plants having pale green leaves, with no distinct pattern on the leaves. Herbicide injury. This is not as common now as in the past, but can still occur. Corn is very susceptible to injury from carryover sulfonylurea herbicides which may have been applied to a previous crop, such as wheat. Carryover depends on soil ph, soil texture, application rates, rainfall, and other factors listed on the herbicide labels. Symptoms include stunting, chlorosis, and an overall sickly appearance. Corn will not grow out of this type of injury. 11

12 ALS herbicide carryover injury to corn. Photos by Stu Duncan, K-State Research and Extension. For more details, see Diagnosing Corn Production Problems in Kansas, K-State publication S- 54, at: Also, see Corn Production Handbook, K-State publication C-560, at: -- Kraig Roozeboom, Cropping Systems and Crop Production Specialist -- Dorivar Ruiz Diaz, Nutrient Management Specialist -- Jeff Whitworth, Extension Entomology -- Doug Jardine, Extension Plant Pathology 4. False chinch bug found in winter canola Clouds of false chinch bugs have recently been reported in some, but not all, winter canola fields in Kansas and Oklahoma. Because of abnormally dry weather, false chinch bugs have infested winter canola fields earlier than expected. High numbers of false chinch bugs are often observed on canola plants at ripening, after yield potential has been determined. Once thought to be a non-factor, false chinch bugs have caused some yield loss this spring considering the current growth stage of the crop. 12

13 False chinch bug on canola. Photos by Josh Bushong, Oklahoma State University Research and Extension canola specialist. 13

14 These insects are first found in the dead plant material (fall growth) on the soil surface. This is where they lay their eggs. As temperatures warm, activity increases and the insects begin to swarm in clouds around and on canola plants. False chinch bugs feed by sucking sap from plants. Damage will include aborted flowers and pods, plants stripped of leaves, and stunting. The Great Plains Canola Production Handbook (MF-2734) lists thresholds at 5 to 10 per head at flowering and 10 to 20 per head at early pod fill. Because false chinch bugs swarm when distributed, it may be hard to count numbers per head. It also is acceptable to consider the thresholds as 20 to 30 per plant at flowering and 40 to 50 per plant at early pod fill. False chinch bugs are most active when the weather is warm and sunny, so avoid spraying on cool and cloudy days. It is recommended to spray close to evening to minimize the impact on beneficial insects. Scout thoroughly because hot pockets may occur in the field. A heavy rain also can dramatically slow the activity of false chinch bug. False chinch bugs can be hard to control so it is important to use enough spray volume to get adequate coverage. For best control with aerial applications, five gallons per acre is recommended. For effective insecticides, consult the Great Plains Canola Production Handbook at: -- Mike Stamm, Canola Breeder mjstamm@ksu.edu 14

15 5. Wheat disease update: Stripe rust, leaf rust, viral diseases * Stripe rust and leaf rust: Stripe rust was reported in Labette, Cloud, and Mitchell counties this week. These reports indicate that the disease is still isolated in small hot spots about 2 feet in diameter or less. The disease had moved to the upper leaves at the Labette County location, but was still restricted to the mid canopy at the Cloud County location. Only trace levels of stripe rust were reported in Mitchell County. In all three cases, the disease was reported on varieties that have the Jaggerbased resistance (Yr17), which was defeated last year by a new race of the fungus that causes stripe rust. A trace amount of leaf rust was observed in Reno County on May 4. The wheat at this location was been under considerable drought stress and the plants were rolling their leaves in response the dry soil conditions. The wheat at this location was heading. * What is the risk of yield loss to rust diseases this year? Finding stripe rust and leaf rust prior to heading is cause for concern and indicates at least a moderate chance of yield loss from disease. I would encourage growers to be checking their fields for signs of disease during the next week. If either leaf rust or stripe rust is present on the upper leaves or in the mid canopy at heading, a fungicide application may be warranted given the higher value of wheat grain. With the dry conditions in many areas of the state, however, it also seems wise to carefully evaluate the yield potential of a field before applying a fungicide. Fields with no disease or those that appear to be under considerable drought stress are not strong candidates for a fungicide application. The hot dry weather forecast for the next few days will slow the development of disease and likely decrease yield potential of the crop. Where the crop is still at the boot stage, I think it would be best to evaluate the condition of the crop and disease situation closer to heading. * Viral diseases Barley yellow dwarf (BYD) appears to be very common this year in south central and southeastern Kansas. I have observed numerous fields with patches of BYD ranging in size from 1 to 20 feet in diameter. Wheat streak mosaic is also being reported in more fields than we have seen in the last 4 years. The disease is severe is some fields near volunteer wheat, and at trace levels in other fields. -- Erick DeWolf, Extension Plant Pathology dewolf1@ksu.edu 6. Wheat Field Day, May 31 Wheat research at Kansas State University will be highlighted at K-State s Wheat Field Day on Tuesday, May 31. The field day will be held at K-State s North Agronomy Farm, 2200 Kimball Ave., directly north of the Bill Snyder Family Stadium in Manhattan. Check-in will begin at 4:30 p.m. The tours begin at 5 p.m. A free dinner will be provided after the tours. Part of the tour will be on trailer, and part will be walking. Assistance will be provided to the walking tour stops for those who need it. 15

16 Those planning on attending can register online at: Registrations can also be made by calling Troy Lynn Eckart, Department of Agronomy, at The registration deadline is May 26. For more information, call your local county Research and Extension office, or Also, see: 7. Comparative Vegetation Condition Report: April 19 May 2 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: 16

17 Map 1. The Vegetation Condition Report for Kansas for April 19 May 2 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows that the Central and Southeast divisions have the most photosynthetically active vegetation. Most of western Kansas continues to show little photosynthetic activity, despite some rainfall in the regions. Morton County is now in exceptional drought status. 17

18 Map 2. Compared to the previous period at this time for Kansas, the current Vegetation Condition Report for April 19 May 2 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows the rapid increase in photosynthetically active vegetation in the Flint Hills. Rainfall and favorable temperatures both contributed to the increase. This increase in photosynthetically active vegetation is also noticeable in northwest Kansas. This area experienced the closest to normal precipitation in April of all the Kansas divisions. 18

19 Map 3. Compared to the 22-year average at this time for Kansas, this year s Vegetation Condition Report for April 19 May 2 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows continuing effects of drought in the western Kansas counties, as well as parts of Harvey, Sedgwick, Sumner, and Cowley counties. Areas from Meade County northeast to the Missouri border are still benefitting from the November moisture, as well as the favorable temperatures. 19

20 Map 4. The Vegetation Condition Report for the Corn Belt for April 19 May 2 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows the gradual increase in photosynthetically active vegetative production along the southern areas of the Corn Belt. A noticeable exception is the Missouri Boot Heel, where cool temperatures and heavy rains have limited photosynthetic activity. 20

21 Map 5. The comparison to last year in the Corn Belt for the period April 19 May 2 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows photosynthetic activity is lagging behind. In Ohio, only one percent of the corn is planted, compared to 61 percent last year at this time. 21

22 Map 6. Compared to the 22-year average at this time for the Corn Belt, this year s Vegetation Condition Report for April 19 May 2 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows while most of the Corn Belt is about average, very low photosynthetic activity can be seen in parts of Minnesota and Wisconsin, as well as eastern Ohio. Saturated ground and cool temperatures are major factors in this delay. 22

23 Map 7. The Vegetation Condition Report for the U.S. for April 19 May 2 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows the impact of the widespread flooding on the Mississippi River Basin. Saturated conditions and cool temperatures also contributed to the low photosynthetic activity in the Ohio River basin, into eastern Pennsylvania. 23

24 Map 8. The U.S. comparison to last year for the period April 19 May 2 from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows much lower photosynthetic activity, particularly in the Central to Southern Plains and the Eastern Corn Belt from Ohio to Eastern Pennsylvania. In Pennsylvania, soil moisture is reported as being 87% excessively wet. Only 14 percent of the spring plowing has been completed, compared to 71% last year. In Texas, the lack of greenness is mainly due to drought. Seventy-six percent of the state is classified as in extreme to exceptional drought. 24

25 Map 9. The U.S. comparison to the 22-year average for the period April from K-State s Ecology and Agriculture Spatial Analysis Laboratory shows the below normal photosynthetic activity in Texas, as well as Eastern Ohio and Western Pennsylvania. Drought is the major factor in Texas, while cool wet conditions are delaying development in the East. In the mountains of Idaho and Montana substantial snowpack remains. 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 25

26 8. April climate summary for Kansas Temperatures: As with March, April was a mild month with wide temperature swings. The statewide average temperature was slightly warmer than normal, with the average a half-degree warmer than normal, placing it at the 48 th warmest April on record. Temperatures reached the 90s in all except the Southeast. Hudson in Stafford County and Medicine Lodge in Barber County reached 99 o F, the warmest reading in the state. Daily record highs were set at 79 locations, and tied at 21 others, an increase in the number of new records from March. However, no all-time record highs were set in April. On the other hand, 26 locations set record low maximum temperatures and 17 tied records. Richfield (Morton County) set a record low daily minimum temperature of 23 o F on the 16 th. Thirty-four locations set new records for daily high minimum temperatures. And, Hutchinson (Reno County) set a new record high minimum for April of 68 o F on the 18 th. Again, statewide monthly average temperatures were only 0.5 o F warmer than normal, with the warmest area in the Northeast with a departure of +1.6 o F. The coolest division was the Northwest division, which averaged 0.7 o F below normal. Precipitation: Preliminary statewide average precipitation was 1.71 inches, which was 69 percent of normal. The Western division fared better than in previous months, but only the Northwest division came close to normal at 94 percent of normal for the month. The Southwest division fared the worst of the western divisions, with an average of only 1.06 inches, or 66 percent of normal. The Central and South Central divisions were the driest locations in April. South Central averaged only 1.02 inches, which is just 41 percent of normal for the month. The eastern three divisions were also below average, with the East Central division having the greatest average precipitation at 2.80 inches, which was 86% of normal. Only 4 days had no location in the state report measurable precipitation, and on an additional nine days the statewide average was zero, with only isolated reports of moisture. 26

27 Table 1 April 2011 Kansas Climate Division Summary Precipitation (inches) Temperature ( o F) April through April Monthly Extremes Division Total Dep. Normal Total Dep. Normal Ave Dep. 1 Max Min 1 % 1 % Northwest West Central Southwest North Central Central South Central Northeast East Central Southeast STATE Departure from normal value 2. State highest temperature in April: 99 o F, Hudson (Stafford County) and Medicine Lodge (Barber County) on April State lowest temperature in April: 16 o F at Tribune (Greeley County) on April Greatest 24hr rainfall in April: 7.6 inches on April 22 at Rossville, Shawnee County (NWS) Source: K-State Weather Data Library -- Mary Knapp, State Climatologist mknapp@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 27