SORGHUM MIDGE COULD BE A PROBLEM

    One of the most damaging insect pests of grain sorghum continues to be sorghum midge and this year’s early wet soil conditions which delayed sorghum planting in some cases, will promote conditions for midge to be a problem this year as grain sorghum will be flowering over several weeks.
    In a brief summary here is what the sorghum midge does to sorghum.  The adult sorghum midge is a tiny, fragile looking, orange fly. Larvae hatch from eggs deposited by a female midge in spikelets of flowering sorghum heads. Each female deposits about 50 tiny, yellowish white eggs during her short lifetime of less than 24 hours. An orange maggot hatches from the egg and feeds on the newly fertilized ovary, thereby preventing kernel development.
    Because midges lay eggs in flowering sorghum heads (yellow anthers exposed on individual spikelets), damage can occur until the entire head or field of sorghum has flowered. The period of midge susceptibility may last from 7 to 9 days (individual head) to several weeks (individual field) depending on the uniformity of flowering.  The good news this year is that most our sorghum fields are uniform in their flowering, due to good soil moisture at planting.
    Fields should be inspected mid-morning to shortly after noon when midge are most abundant on flowering heads.  The simplest and most efficient technique for detecting and counting sorghum midges is careful, close-range inspection of all sides of a randomly selected flowering head.  Since they are relatively weak fliers and rely on wind currents to aid their dispersal, adult sorghum midges are usually most abundant along field borders.
    The need to apply insecticidal control is based on the number of adult midges during the flowering period, and based on today’s grain prices and potential yield, an average midge density of 1 midge per panicle (head) or greater would probably warrant insecticide treatment. Insecticide residues should suppress sorghum midge egg laying for 1 to 2 days after treatment. If adults are still present 3 to 5 days later, immediately apply a second treatment. If midges are present the day following treatment, it does not mean you do not have protection for the heads; midges could be re-infesting the field, which is common.
    More information about managing sorghum insects can be found at the AgriLife Bookstore found on the Internet website;  http://agrilifebookstore.org/ 
 by entering publication number B-1220.

COTTON AT CRITICAL GROWTH STAGE

    Last week I hosted a Cotton Workshop that focused on the phase of cotton growth from first square to first bloom, the current stage of our cotton crop.  Since this growth stage is so important, I thought I would review some basic cotton physiology as it relates to current growing conditions.
    Here are some important pointers to consider when managing cotton during this growing stage.  Currently the heat units for our cotton crop are very near normal and early planted cotton is at least at the six to seven node stage and setting squares. This cotton should be at first bloom by the first week of June.  As a general rule, for every 50 heat units accumulated, the cotton plant will produce a new node.  Moreover, at this time the cotton plant is continuing to develop an extensive root system and will do so until about one week after flowering.
    It is important to note that up to 85% of the lint yield will be determined by first bloom, and up to 80% of that yield will come from the first fruiting positions on the cotton plant.  So now is the time to see that our cotton has optimum growing conditions and we need to protect that first fruiting position.
    Cotton insects during this growth stage that warrant serious considerations are cotton fleahoppers at which the treatment threshold is 15 per 100 terminals. In addition, aphids can also be a problem, and if more than 50 aphids per leaf persist for more than seven days then treatment for them is probably warranted.
    One of the goals during this growing stage should also be to develop the best plant structure possible.  To achieve that, we need to consider the growth potential of the plant.  Ultimately the, final cotton plant height here in the Coastal Bend should be 30 to 35 inches for 30-inch rows, or a  rule-of-thumb used to predict optimum plant height is to multiply the row width times 1.1.  With these limits, one can ensure that row middles are covered but not to such a degree that boll rot will develop.
    The cotton plant produces a new node in the terminal every three days. Each new internode continues to extend and thicken over the next 12 to 15 days, depending on temperature and growing conditions. The most rapid expansion (85 percent) occurs in the first six to 10 days. The arrival of heavy rains or use of irrigation will cause cotton to increase nitrogen uptake which can  result in rapid growth.
A cotton plant will do a good job of regulating its own height if there is a lack of  heavy rainfall and the presence of a heavy fruit load during this time period.
    To help control rapid growth the product Mepiquat chloride (MC) is used. MC will help retard excessive plant height as it suppresses stem elongation of newly formed internodes.  The minimum MC concentration in the plant necessary to provide a maximum level of reduction is 12-15 ppm.  It is extremely important to make the first applications of MC early enough, usually around  Matchhead Square to keep the plant’s growth under control.  For more information about using MC to manage cotton plant height consult the publication found at this web site; http://safiles.tamu.edu/agronomy/cotton/b6042.pdf
    So at the conclusion of this growth stage that is first bloom, one can count the nodes above white flower (NAWF) to determine just how well the crop is doing.  In fact, we would like to see that number around eight or nine nodes.  If that number is at five, the cotton plant is in trouble and production of additional squares will end as this is known as “cut out.”  If the plant has nine NAWF at first bloom, this is an indicator that the plant has a lot of “horse power” and great yield potential. So lets all hope that around June 10 our cotton plants have eight or nine NAWF, and of course a little more rain between now and then will help achieve that goal.

HAY QUALITY INFLUENCED BY SEVERAL FACTORS

With an early wet Spring, there have been several people able to make hay in the last few weeks which brings me to today’s topic,  factors that influence hay quality.  Hay varies in quality more than any other harvested feed crop. Hay quality can vary widely, even when composed of one and the same species, when grown in the same vicinity, and when grown and cured under similar conditions.   Moreover, hay can look good, i.e., dark green color, and still be low in quality, or can look bad, that is not have a good dark green color, and still be good quality.  The best way to determine what quality you have is to have it tested by a forage testing lab.
    Factors that determine hay quality include stages of maturity at harvest, soil fertility, nutritional status of the plant, available moisture during the growing season, season of the year, ratio of leaves to stems and stem size, weed control, foreign matter, harvesting, weather at harvest and storage. Of all the factors that influence quality, stage of maturity or age of the plant at harvest is the most important.  In fact, about 70% of the quality of hay is determined by stage of maturity at harvest. As a plant matures toward heading, flowering and seed formation, the growth pattern changes from leaf production to hard stem formation.
    Since leaves are more digestible than stems and contain most of the nutrients, the higher the leaf content, the higher the quality.  The younger the plant, the greater the proportion of leaves, thus a higher quality plant.  A quick visual method to determine maturity can be done by looking for seed heads. As a simple guide, grass hays with only a few immature seed heads is high quality, and as the number and amount of mature seed in the heads increase, the quality decreases.
    Soil fertility is also an important factor in determining the ultimate quality of hay.  Nitrogen fertility rates for grasses greatly influence the crude protein levels in forages harvested at the right stage of maturity.  The nitrogen content of a forage is a direct measure of its protein content. The nitrogen that is extracted from a forage is multiplied by a factor of 6.25 and reported as percent crude protein. Thus, a forage containing 2 percent nitrogen contains 12.50 percent crude protein.  Phosphorus, potassium and other nutrients are also critical to maintaining stands and producing quality hay. A soil test should be taken once a year to determine the amount of plant nutrients remaining after the previous years productions to replace those elements removed by harvest.
    So when is the best time to make hay?  The proper stage of growth for harvesting forages is the time when the greatest amount of total digestible nutrients per acre may be obtained. This usually represents the best compromise between quality and yield.  Generally, the younger the crop at the time of harvest, the higher the quality but the lower the yield. The more mature the crop at time of harvest, the higher the yield but the lower the quality.  Research also indicates that forages are higher in quality during spring and fall and lower in quality during mid-summer.
Recent experiments (USDA) indicate that cattle prefer afternoon cut hay over morning cut hay. Since cells make sugars and carbohydrates in the presence of sunlight, afternoon cut hay may contain a higher percentage of highly digestible sugars and carbohydrates. Plants cut in the morning have partially depleted the supply while respiring or using energy through the night.
    Color is not always a good indicator of quality, as it usually is a good indicator of the curing process following cutting.  A bright green hay usually means the hay was cut at a desirable stage of maturity and cured rapidly.  The yellow color that is often seen, is a sign that there was a significant amount of sun bleaching, but quality is not seriously reduced.  A brown colored hay usually indicates that excessive moisture fell on the hay during the curing process, and usually has a musty odor.  Odor can also be an indicator of reduced quality.  Hays with off odors like mildew, mustiness or rotten odors can be an indicator of reduced quality and poor acceptance by livestock.
    Another factor that can impact hay quality is the presence of foreign matter.  Yes, weeds are the biggest problem, and sometimes even injurious materials like threeawn grass seedheads, sandburs, and toxic plants can be found.  When buying hay, you should always look for foreign matter. Finally, soft, pliable hays are usually more palatable than hard, firm hays, as this usually indicates the lack of lignin or stem maturity.  
    The goal of harvesting should be to maintain the highest nutritive quality as possible through cutting at the proper stage of maturity, promoting rapid drydown, maintaining high leaf content and timely baling at the right moisture content.  Bacteria and fungi that cause hay to deteriorate, need moisture to grow. If hay is baled at a too high moisture, bale heating occurs shortly after harvest. Microbes are not able to reproduce if moisture levels are below about 14%.
Small 60-70 pound bales can be baled at 16-18% moisture while hay stored in large round bales
needs to be dryer (14-16%) at baling since moisture is unable to escape from the center of a large bale.