{"id":204,"date":"2018-09-10T16:11:00","date_gmt":"2018-09-10T20:11:00","guid":{"rendered":"http:\/\/site.extension.uga.edu\/forageteam\/?p=204"},"modified":"2018-09-10T16:11:00","modified_gmt":"2018-09-10T20:11:00","slug":"dealing-with-forage-diseases","status":"publish","type":"post","link":"https:\/\/site.extension.uga.edu\/forageteam\/2018\/09\/dealing-with-forage-diseases\/","title":{"rendered":"Dealing with forage diseases"},"content":{"rendered":"
By Adam Speir<\/strong><\/div>\n
Madison County CEC<\/em><\/div>\n
<\/div>\n
For most forage producers, disease is usually the least dealt-with component of the \u201cforage pest-trifecta\u201d of weeds, insects, and diseases. Just like humans, forages have a general tendency to withstand disease pathogens that are present in the environment. However, situations can develop where disease issues arise and producers are left with trying to determine what course of action to take to treat the issue, or more appropriately, what course of action to prevent the issue from happening in the future. We\u2019ll discuss a few examples here and what practices can help prevent disease problems in your forages.<\/div>\n
<\/div>\n
Common Issues <\/strong>\u2013 There are several diseases to be aware of that are more common for producers across Georgia.<\/p>\n
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Leaf Spot\/Blight in Bermudagrass (www.thomascountyag.com)<\/figcaption><\/figure>\n<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Leaf Blight or Leaf Spot<\/strong> (Helminthosporium or Bipolaris)<\/em><\/strong> \u2013 This disease can be seen in Bermudagrass and Bahiagrass across the state. It can be identified by circular lesions on leaves and are more numerous near the collar of the leaf blade. The lesions are irregularly shaped and brownish-green to black. The disease can also infect crowns, rhizomes, and stolons of plants which can result in more substantial damage. When the disease becomes severe, and as leaf spots begin to coalesce, you will notice large, irregularly-shaped brown or tan patches in fields and stands will thin out. These diseases can occur almost any time of the year, but are seen most commonly in late summer and early fall with high humidity levels.<\/div>\n
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Heavy damage from Leaf Rust
(Jeremy Kichler \u2013 Colquitt County Ag Report)<\/figcaption><\/figure>\n

\u00a0 Leaf Rust (Puccinia)<\/em><\/strong> \u2013 At first glance, leaf rust may appear similar to leaf spot diseases in grasses, and sometimes use of a microscope is needed to identify one or the other. But at closer inspection, rust lesions will most often appear as orange or red pustules or raised areas on leaves and stems. Rubbing an infected leaf will leave rust-colored areas on your fingers or clothing.<\/div>\n

<\/div>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Dollar Spot<\/strong> (Sclerotinia)<\/em><\/strong> – This disease is more of a concern for turfgrass managers than forage producers, but dollar spot can still affect tall fescue as well as bermudagrass and bahiagrass. Dollar spot will result initially in irregularly shaped lesions with dark brown borders on leaf tissue. Lesions may be up to an inch long and usually on the leaf margins. The fungus can develop mycelium that resembles spider webs and can take on a \u201ccotton ball\u201d appearance as it spreads. As the disease progresses, large patches in the grass can die, with the leaves collapsing producing sunken areas of dead grass 2 to 12 inches in diameter. The fungus will directly affect the uptake of water and nutrients and case roots to thicken, stop growing, and turn brown. This disease can be found most often in late spring and early summer.<\/div>\n

Management and Control Strategies<\/strong> \u2013 Unlike other components of the previously mentioned \u201cforage pest-trifecta\u201d where chemical control options exist, there are no legal, effective, or economical fungicides to control any of the common forage disease issues you might encounter. This leaves management or \u201ccultural practices\u201d as the only tools in your toolbox. As also mentioned previously, disease pathogens are almost always present in the environment \u2013 it is most often a combination of adverse environmental conditions and stressed plants that is the main factor resulting in disease problems.<\/p>\n

From a management perspective, there are five practices that are effective in reducing the risk of disease infection \u2013 1) Selecting a resistant variety, 2) maintaining soil fertility, 3) managing irrigation, 4) removing thatch, and 5) harvesting forage in a timely manner.<\/p>\n

1) Variety Selection \u2013 This is especially important in Bermuda and also bahiagrass varieties, as some varieties are more\u00a0inherently resistant to some fungal diseases. Varieties such as Coastal, Tifton 44, and Tifton 85 were bred to be more\u00a0resistant to leaf spot diseases than what has been observed in common bermudagrass or Alicia. In bahiagrass, Argentine\u00a0 has been shown as less susceptible to dollar spot than other varieties like Tifton-9 or TifQuik. If deciding to seed or plant new establishments, consult with your Extension agent or company representative to discuss disease tolerances.<\/p>\n

2) Soil Fertility \u2013 This is probably one of the most important management principals to help prevent potential issues. Many disease issues, especially in warm season grasses, are tied to poor fertility \u2013namely potassium deficiency. Timely soil\u00a0sampling and good fertility management can help any variety of forage to be more stress tolerant and disease resistant. It may also be useful to collect tissue samples from diseased forages to determine if potassium is deficient in tissue if a soil\u00a0analysis is not available.<\/p>\n

3) Irrigation \u2013 Almost every forage disease issue is related to water \u2013 whether it be overly wet conditions from rainfall, or\u00a0\u00a0ponding due to poor soil drainage. Too much water and fungal diseases almost always go together. While it is difficult to manage water in a dryland situation, managing irrigation schedules to prevent plants being wet for several hours at a time is\u00a0\u00a0preferred. If running irrigation, many producers have had success by turning off irrigation from mid-afternoon until the\u00a0\u00a0following morning, so as to prevent having grass being wet going into evening and staying wet until the following day.<\/p>\n

4) Thatch \u2013 In many situations, a buildup of thatch material can contribute to disease issues. The abundant organic matter\u00a0and inhibition of airflow to dry out wet material helps create a suitable environment for fungal growth and disease outbreaks. Also, thick plant material can serve as a harbor for spores and future disease development. In some situations,\u00a0\u00a0burning of fields in the springtime to reduce thatch is recommended.<\/p>\n

5) Timely Harvest \u2013 Related to the previous point, timely harvest can prevent a buildup of plant material that would allow\u00a0for disease development. Also, leaf spot and other diseases are more prone in under-grazed or over-grown situations, so timely harvest will keep plants actively growing and could help keep older plant material from becoming infected.<\/p>\n

In an ideal world, diseases are not a common forage production concern. But things are never ideal. In a good weather year, diseases may be minimal. But in a very wet year, disease may be much more common. In these situations, implementing the strategies mentioned can help prevent a potential problem from becoming a serious, even devastating problem.<\/p>\n","protected":false},"excerpt":{"rendered":"

By Adam Speir Madison County CEC For most forage producers, disease is usually the least dealt-with component of the \u201cforage pest-trifecta\u201d of weeds, insects, and diseases. Just like humans, forages have a general tendency to withstand disease pathogens that are present in the environment. However, situations can develop where disease issues arise and producers are […]<\/p>\n","protected":false},"author":75,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[69,16],"tags":[70],"class_list":["post-204","post","type-post","status-publish","format-standard","hentry","category-disease","category-warm-season-perrenials","tag-diseases"],"_links":{"self":[{"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/posts\/204","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/users\/75"}],"replies":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/comments?post=204"}],"version-history":[{"count":3,"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/posts\/204\/revisions"}],"predecessor-version":[{"id":209,"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/posts\/204\/revisions\/209"}],"wp:attachment":[{"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/media?parent=204"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/categories?post=204"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/site.extension.uga.edu\/forageteam\/wp-json\/wp\/v2\/tags?post=204"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}