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Crop Development Wheat Growth Stages Still, the rate of growth development for any wheat variety is directly related to temperature (accumulated heat units), except under extremely dry conditions. Thus, by knowing the planting date for wheat, and by tracking weather data, one can predict growth development and plant stage. This helps growers make timely treatments to control weeds, top dress fertilizer, control diseases, and other management decisions. The 2005 Hard Red Spring and Durum Wheat Management Calendar on pages 12-13 can assist growers to make management decisions by growth stage. The North Dakota Agricultural Weather Network (NDAWN) can help growers keep track of weather and growing degree days. On NDAWN’s Internet home page (http://ndawn.ndsu.nodak.edu) click on the “applications” link. There, you will find a number of applications for using NDAWN, including:
Consult with an agronomist, certified crop adviser, or county extension agent/educator for more background on growing staging crops, or about how to apply NDAWN information. NDSU has a publication online, “Identifying Leaf Stages in Small Grains,” at www.ext.nodak.edu/extpubs/plantsci/weeds/w564w.htm. The University of Minnesota publication “Growth and Development Guide for Spring Wheat” can be found online at www.extension.umn.edu/distribution/cropsystems/DC2547.html. Corn Growth Stages Each leaf stage is defined according to the uppermost leaf whose leaf collar is visible. Loss of the lower leaves will begin about V6 due to increased stalk size and nodal root growth. To determine the proper leaf stage after lower leaf loss, split the stalk lengthwise and inspect for internode elongation. The first node above the first elongated internode is generally the fifth leaf node. This fifth leaf node can be used as a reference point for counting the top leaf collar. Vegetative Stages Stage Description V1 One leaf with collar visible V2 Two leaves with collars visible V(n) (n) leaves with collars visible VT Last branch of tassel is completely visible
Reproductive Stages Stage Description R2 Blister - kernels are white and resemble a blister in shape R3 Milk - kernels are yellow on the outside with a milky inner fluid R4 Dough - milky inner fluid thickens to a pasty consistency R5 Dent - nearly all kernels are denting R6 Physiological maturity - the black abscission layer has formed Sources: Iowa State University, Purdue Soybean Growth Stages The following divides soybean plant development into vegetative (V) and reproductive (R ) stages. With the exception of the first two stages, the (V) stages are designated numerically as V1, V2, V3, etc. through V(n) where (n) represents the number for the last node stage of a specific variety. The (n) will fluctuate with variety and environmental differences. The eight R stages are simply designated numerically. The V stages following VC are numbered according to the uppermost fully developed leaf node. Start with the unifoliolate leaf node when counting the number of fully developed leaf nodes. A leaf node is fully developed when the leaf above it has leaflets which are fully unrolled. That is, the leaflet edges are no longer touching. Vegetative Stages Stage Description VE Emergence VC Cotyledon V1 Unifoliolate and first trifoliolate leaves are fully developed V2 Unifoliolate and first two trifoliolate leaves are fully developed V3 Unifoliolate and first three trifoliolate leaves are fully developed V(n) Unifoliolate and (n) trifoliolate leaves are fully developed
Reproductive Stages Stage Description R1 Open flower at any node on the main stem R2 Open flower at one of the two uppermost nodes on the main stem with a fully developed leaf R3 Pod is 3/16 inch long at one of the four uppermost nodes on the main stem with a fully developed leaf R4 Pod is 3/4 inch long at one of the four uppermost nodes on the main stem with a fully developed leaf R5 Seed is 1/8 inch long in the pod at one of the four uppermost nodes on the main stem with a fully developed leaf R6 Pod containing a green seed that fills the pod cavity at one of the four uppermost nodes on the main stem with a fully developed leaf R7 One normal pod on the main stem that has reached its mature pod color R8 95% of the pods have reached their mature pod color Sources: Iowa State University, Purdue Percent of Yield Produced by Various Soybean Growth Stages
Soybean Maturity 101 Relative maturity ratings consist of a number for the maturity group designation such as: (000-early, 00- mid early, 0-mid or 1-late) and followed by a decimal and another number, ranging from .0 to .9, which indicates maturity rankings within each maturity group. Each 0.1 change in group rating represents approximately 0.75 to 1 day later maturity. For example, the variety Jim is indicated as 00.6, making it a medium maturing variety in the 00 group. Walsh would be a 0.0, making it one of the earliest varieties in the 0 group whereas Sargent is a 0.8 making it one of the later varieties in the 0 group. Few if any group 1 soybeans are currently planted in N.D. except in the extreme southeast part of the state. Bloom Key Soybean Development Stage Soybeans are at 50% bloom when an open flower can be found on every other plant in a row. Flowering, unlike maturity on soybeans, begins toward the bottom of the plant (at the third to sixth node) and then progresses upward and back downward. Branches off of the main stem will flower a few days later than the main stem. While flowering begins at the base of the plant and proceeds to the top of the plant, physiological maturity of the beans will progress anywhere on the plant stem. Normally, soybean pods will be mature in the middle or top of the plant and down. Thus, remember to check pods toward the bottom of the plant when determining if harvest time has come. Flowering of soybeans is an important time in bean growth and development. At stage R2, full bloom, each plant has accumulated about 25% of its total dry weight and nutrients; it has attained about 50% of its mature height; and, it has produced 50% of its total mature node number. This later flowering stage begins the period of very rapid N-P-K and dry matter accumulation that will continue through R6. Also, during flowering, the soybean plant gears up on its nitrogen fixation in order to provide for the demands of the plant. Scout for disease and insect problems (aphids) during this critical early time period of flowering. Canola Growth Stages
With herbicide tolerant canola, one has to pay special attention to plant stage for last application. For Roundup Ready canola, application can be made from seedling emergence to bolting (5 - 6 leaf). For Liberty Resistant canola, the application can be made from seedling stage up until early bolting stage (3 .2). For Clearfield canola varieties, Beyond application can be made up to just prior to bloom. Canola in the 5.3 to early 5.4 stage should be near or at swathing stage. These stages change very rapidly during the ripening period if temperatures are warm and under dry conditions. Diagnosing plant problems NDSU – Waldron Hall, Room 206, PO Box 5012, Fargo, ND, 58105, ph 701.231.7854, email: diaglab@ndsuext.nodak.edu, web site: www.ag.ndsu.nodak.edu/diaglab. Fee-based services include insect, weed, disease identification and control recommendations, herbicide injury diagnosis, and soybean cyst nematode screening. UM - Plant Disease Clinic, St. Paul, ph. 612.625.1275. Web site: www .extension.umn.edu/distribution/cropsystems/DC3170.html. Fee-based services include insect, plant, disease, virus ID, as well as seed quality testing. SDSU – Oscar E. Olson Biochemistry Labs, Brookings, ph 605.688.6172, web site: http://anserv.sdstate.edu. SDSU Plant Disease Clinic: http://plantsci.sdstate.edu/planthealth (click on Plant Disease Clinic). Ph 605.688.5157 Link to more private and public testing labs can be found online: These labs (as well as professional crop consultants/certified crop advisers) can help determine key factors that affect crop productivity, such as: Soil organic matter tests – Knowledge of the organic matter level will serve as a guide in selecting an effective herbicide and rate of application, as well as helping to assure crop safety. Testing once every five years should be adequate. Herbicide spray water analysis – High salt levels in spray water can reduce weed control in nearly all situations. Calcium, and to a lesser degree, magnesium, are antagonistic to 2,4-D and MCPA amine, dicamba, and glyphosate. Plant tissue analysis – This indicates the nutrient status of plants at the time of sampling, serving as a monitoring tool for determining the adequacy of current fertilization practices. Plant tissue analysis will also detect unseen nutrient deficiencies and may confirm visual symptoms of deficiencies. Toxic levels also may be detected. Combined with soil test information, a plant analysis report can help a producer tailor fertilization practices to specific soil-plant needs. Evaluating Hail Damage, Crop Recovery Hard red spring, durum – Wheat in growth stages prior to early boot (flag leaf is just out) will have regrowth from tillers if the plants are not totally destroyed. After the head emerges, ability to regrow declines rapidly. The more advanced wheat is at the time of hail, the greater the yield loss. Prior to boot stage, it may be best to leave the crop if stems remain. Depending on rainfall, fertility, soil moisture remaining and severity of damage, yields may vary from 20-70% of normal. Hail adjusters will adjust crops after boot stage so a decision can be made on their analysis. Winter wheat – Hail damage to winter wheat in bloom or milk stage can be adjusted. Losses are proportional to percentage stem breakage. If insured, use adjustment as basis of decision. Winter wheat makes good hay if yield losses are such that harvest costs will not be repaid. Maturity will be delayed in hail damaged winter wheat. Lentils, dry beans, flax – These crops will recover from hail if green material remains above the area of the first leaf. Buds along the stem will regrow following destruction of the growing point. Delay in maturity is a major factor in final yield and quality, especially in dry beans. Flax will tolerate frost while dry beans will not. Lentils do not tolerate heat well and yield loss may occur if flowering occurs during hot weather. Use of fungicide and micronutrients may help recovery. However, there is no economic data on this practice in N.D. In the corn belt, economic yields were obtained about 50% of the time when treating soybeans. Canola, mustard – plantings in the seedling stage can have stands reduced to one-third of normal and produce acceptable yields. Plants hailed prior to flowering suffer yield decline because of loss of leaf area (the crop will still produce 60-80% of normal yield if enough material is available for regrowth). Seed yield loss in canola is 25% of percent of leaf area lost. Plants injured in early flowering seldom die, however, yield loss can be severe. Early maturing canola (B. campestris) that is similar to yellow mustard in maturity suffers increasing yield loss as flowering progresses. Plants that have been flowering 7-14 days will have yield losses due to hail equal to percent of branches lost. If 70% of branches are lost, 60-70% of yield will also be lost. Corn – Corn will tolerate total defoliation and regrow if the growing point is intact. The growing point remains below ground 2-3 weeks after the plant emerges (4-leaf). If the growing point is not damaged, corn will recover and perform better than replanted corn. Split the stalk down the center and inspect the growing point. If normal, it will appear white in color and firm in texture. Injured growing points will appear brown or discolored 2-3 days following the hail. Complete loss of leaves early to corn when small usually does not greatly affect grain or silage yields. Stalk bruising and rain splash will cause more stalk disease and smuts to occur. Lodged corn should recover. Some “goose necking” of lodged plants can occur but is usually not serious. Maturity delays depend on defoliation damage and temperatures throughout the season. Continued warm weather will minimize maturity delays. Sunflower – Total defoliation of young sunflower plants up to bud stage usually causes little yield loss if storm damage is minimal. Damage to the terminal bud will delay maturity, cause yield losses and production of multiple heads. Multiple heads do not yield well and may lodge or break easily. Stem bruises, if severe, can open plant to stalk diseases and possible lodging problems later in the season. Sunflower Development, Growing Degree Days Check the NDSU NDAWN web site for the 2005 Growing Degree Units in various locations in N.D. (http://ndawn.ndsu.nodak.edu/sunflowerdd-form .html). Just enter in the planting date and the current date for your location.
Soybeans – Hail that accumulates without destroying the stalk of soybeans (corn and dry beans as well) may freeze the growing point. If no new growth appears within five days and the growing point is dark and soft, the plant has been killed. The growing point of beans is located in the top of the plant and in leaf axils. Growing points of beans are easily damaged by hail soon after emergence. Regrowth will not occur if hail stones cut the stem off below the cotyledonary node. If the top of the plant is damaged, regrowth can occur from one or more axillary buds. Bean stems may be bruised or broken. The damage may not be severe enough to kill the plant. However, the plant may lodge later as the callus tissue is weak and cannot support the pod weight. Reduction in stands to four plants per linear foot of row can still produce fair yields. IPM Surveys Track Growing Season Field Pests |
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