\ r £ 'Mill V*(Vl it*.' r, , A36-L«ncMtef Farming, Saturday, July 5, 1997 Tobacco (ConUnuad from Page A 1) against the blue mold. Anderson and Yocum said to a group of at least ISO that the strain of blue mold currently in Lancaster County is believed to be a Ridomil-resistant variety that is also believed to have been intro duced a month ago through two shipments of transplant-size tobac co plants from North Carolina. Ridomil is also a fungicide, which had been approved for use in seed beds for tobacco. A new version of the fungicide, Ridomil- Gold, has not been approved for use in seed beds because some blue mold has become resistant. Some businesses in Southern states such as Florida and North Carolina have developed that emphasize raising tobacco plants in floating seed beds. The seed bed medium floats above water and the moisture is wicked up to the seed and plant The warm, and constant moisture environment presents optimum conditions for the growtl\ of fun gus. Ridomil use allowed growers to use the floating beds to produce a higher number of quality tobacco plants for sale for transplanting into fields. However, with the constant and widespread use of Ridomil in the floating beds, the blue mold deve loped resistance. Therefore, the newer version of the fungicide can no longer be used in seed beds, although the remain ing stocks of the older version of Ridomil are still labeled for such use. During a spring tobacco meet ing, Yocum and Anderson had warned local growers about pur chasing and using transplants that may possibly carry the resistant variety of disease. Apparently, their warnings were not completely heeded. Yocum said that while blue mold is not a surprise disease in the area, the traditional variety (which continues to be controlled by Ridomil in the field) normally only appears in the state later in the season. He explained that the micro scopic spores of the blue mold become airborne and travel north and east, carried with storms. The prevailing wind patterns in North America usually take the shape of a giant “U” stretching from the Northwest down south through the Mid West or further, and then back up into the Northeast Through the seasons, the post ion of the “U” changes north and south across the continent. The “U” generally travels north and south, as the earth changes its rela tionship to the sun. Here, in central Pennsylvania, sometimes storm systems travel off the East Coast farther south and sometimes farther north. Sometimes the northeast direc tion of the “U” remains to the west of central Pennsylvania, taking a course up the Ohio Valley, through northwest and northcentral Pennsylvania. Blue mold cannot tolerate cold temperatures and only overwinters in southern North America, such as in wild tobacco in Texas, in southern Florida, in Cuba, and in South America, Yocum told the group. The spores (the “seeds” of fungi are called spores) are carried with the wind and generally creep north and eastward as the “U” dips farth er south as the summer progresses. Some years central Pennsylva nia is spared, other times not Growers States involved with tobacco production have long recognized this relationship between the spread of airborne disease and weather patterns and have set up a reporting system, so that the spread of disease can be antici pated and growers can take appro priate action. Ycoum said that some of the other states involved with monitor ing diseases have also had the dis ease. though they have both types, resistant and nonresistant. The nonresistant variety is usu ally the first one to show up, car ried by the winds and steams. It was not yet detected in Pennsylva nia and the weather was recently not conducive to its movement here. That is part of the reason why officials believe the blue mold was transported into the state through contaminated tobacco transplants trucked into the state. Yocum said that this year the fungus appeared very early in Flor ida and jumped north. “We would have gotten it any way, because it travels with storm fronts,” Yocum said. “All (that happened with transporting infected plants) was hasten deve lopment of the disease.” In order to fight this fungus, the Pennsylvania Department of Agri culture petitioned for and received emergency approval for the off label use of the Acrobat MZ fungicide. According to Yocum, most of the transplants from North Caroli na did have the blue mold. Since then, Anderson said he has been on SO to 60 farms and said he can find it in almost every seed bed. He said that if the rains come as had been forcast that it could soon be everywhere in the county. It started raining during the meeting. Nonirrigated fields in the region have been very dry, causing some spiking of com. Tliat has kept the mold from becoming widespread in fields. The mold spores can fall with the rain and need the moisture on the surface of the tobacco leaf in order to grow. The disease causes spotting and browning of leaves and the dam age is irreparable, though the fun gicides can stop further damage. According to Yocum, there are two fungicides that can be used Dithane DF as a preventative, and Acrobat MZ which has preventa tive and limited systemic properties. (Dithane is in the mancozeb family and it is also in Acrobat MZ.) The systemic properties of Acrobat MZ can kill the mycelium (the actual body of the fungus that is generally not seen) in the plant and thus has some curative proper ties, but it’s only systemic locally. Both Acrobat MZ and Dithane DF have strong preventative prop erties because they kill the spores when they land on the leaf. The fact that the main strategy for fighting blue mold depends on interacting with the disease on the surface of the plant means that spraying techniques need to ensure complete plant coverage. Sprayers will probably need to have different nozzles and arms attatched in order to effectively coat the plant Many of the tobacco growers in the region use mule power, and Anderson and Fleming rigged Beiler’s boom sprayer to tackle eight rows. Starting with a boom sprayer (Turn to Page A 37) Keys to Success for Controlling Blue Mold in Tobacco with ACROBATMZ s Initiate ACROBAT MZ applications as recommended by the Blue Mold Advisory Use ACROBAT MZ in a preventative foliar spray program to manage blue mold v Direct application of ACROBAT MZ to the plant (not the soil) and provide thorough coverage over leaves and bud of plant Use hollow cone or disk-core nozzles to break spray into small droplets for thorough plant coverage s Use multiple nozzles per row that direct the spray over the entire plant s Add drop nozzles as the plant grows to insure thorough plant coverage v Use high volume sprayer v' Spray pressures greater than 100 provide <he best results s Spray only as many rows pet pass wit), the sp'ayoi as the ec.uip.n j ■< will effectively deliver fungicide to the target leaves. Make application to dry foliage ACROBAT MZ is ramfast in 3 hours •s Keep the spray interval close (5-7 day intervals) under strong disease pressure Refer to ACROBAT MZ product label for complete application and rate details Application Rates and Timing for Blue Mold Control with ACROBAT MZ in Field Grown Tobacco Weeks of Growth Rate of ACROBAT MZ Water Output After Transplant (Pounds of Product/Acre) (Gallons/Acre) Recently transplanted to 5 2q 3 weeks after transplanting 3- weeks after transplanting n (knee high) _ 4- weeks after transplanting _ „ n (waist high) _ _ 6-7 weeks after transplanting _ fln (chest high) _ 7 weeks after transplanting _ ... 2 o iuu and beyoad Note Above directions are for dilute sprays If concentrate sprays are used, adjust rate and volumes proportionately Application to Small Plants (transplanting up to 3 weeks) ♦ Use one hollow cone nozzle over the ♦ row and one on each side of the plant ♦ Apply 20 gallons per acre of water volume ♦ Spray at pressures above 60 PSI to achieve good droplet dispersion The Cost Of Spray Nozzle Conversion 8 Rows = 9 Drops on existing Boom Sprayer Modification Costs Existing spray boom had 15 spray nozzles on 20 inch center to cover 285 inches (23 75 feet) Modified spray boom has 17 spray nozzles on 19 inch center to cover 304 inches (25.33 feet) Drops Part No Description Quanity Unit Costs Total Costs 2135415NY8 15" Hose Drops 8600214NY8 Swivle Bodys DVP6 Orifice Disc DC23NY Core 8079PP50 Strainer 33942 Nozzle Blank Cap Rows DVP6 DC23NY 8079PP50 3NTTI2 33942 3812 AA11134 Total Cost = $126.41 Cost / Row = $15.80 This cost information for converting to cone spray nozzles to ensure top ana bot tom tobacco leaf protection when spraying the Acrobat MZ product was compiled by Lancaster County Penn State Extension Agent Robert Anderson and Mike Fleming, with American Cyanamid, makers of Acrobat MZ. Compared to the value of the crop, the cost for purchasing the proper spray heads is miniscule. While the specific spray head manufacturers are in no way endorsed by Penn State, these were selected because they will perform the Job. In addition, according to John Lake, with the Pen nsylvania Department of Agriculture Bureau of Plant Industry, while Acrobat MZ was similarly approved for use against blue mold last year (though it wasn’t really needed because weather patterns protected the area), it was approved this year with the sti pulation that spraying equipment provide complete plant coverage. The Acrobat MZ has only local systemic properties and new tobacco plant growth is not protected unless it too is sprayed. Acrobat MZ stops spoliation, and thus can stop the blue mold, which is believed to be a variety already resistant to another common fungicide, Ridomil. Orifice Disc Core Strainer Nozzle Tee Nozzle Blank Cap Poly Nozzle Nut Clamp lip vf' $3.8250 $4.9500 $0.5700 $0.6225 $0.5325 $0 1600 1 6 1 6 1 6 $0.5700 $0.6225 $0 5325 $0,4200 $0.1600 $0 0800 $2.1975 $34.43 $44 55 $9.12 $9.96 $8.52 $0.32 $lO6 90 $4 56 $4 98 $4 26 $0.84 $0.32 $0.16 $4.40 $19.52
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