Plant Pathology Commons^™

Chemical Control Of Turfgrass Diseases 2014, Paul Vincelli, Gregg Munshaw

Agriculture and Natural Resources Publications

Turfgrasses under intensive management are often subject to outbreaks of infectious diseases. Diseases usually are most damaging when weather or cultural conditions favor the disease-causing agent but not plant growth and vigor. Cultural conditions that predispose turfgrass to diseases include close mowing, inadequate or excessive nitrogen fertility, light or frequent irrigation, excessive thatch, poor drainage, and shade.

Good turf management practices often greatly reduce the impact of disease by promoting healthy plants that are better able to resist infections. Even under good management, however, diseases sometimes cause excessive damage to highly managed turfgrasses. The proper use of fungicides in these …

Managing Spring Dead Spot Of Bermudagrass, Paul C. Vincelli, David Williams

Agriculture and Natural Resources Publications

Spring dead spot is the most destructive disease of bermudagrass in Kentucky. The most serious outbreaks occur under high maintenance conditions; e.g., high nitrogen fertility, low mowing height, and frequent traffic. Moderate to severe outbreaks can occur under low-maintenance conditions as well.

High levels of resistance to spring dead spot in bermudagrass varieties have not yet been demonstrated experimentally. Limited data suggest that those varieties with best winter hardiness are somewhat less susceptible to the disease. To date, no confirmed cases of spring dead spot have been documented in “Quickstand” bermudagrass, which may indicate that this variety will suffer less …

Patch Diseases In Kentucky Bluegrass Lawns, Paul C. Vincelli, A. J. Powell Jr.

Agriculture and Natural Resources Publications

“Patch diseases” can be very destructive when Kentucky bluegrass is grown under intensive management. Two patch diseases with similar symptoms can occur. Necrotic ring spot often appears in early summer. Summer patch, the more common disease in Kentucky landscapes, develops in middle to late summer.

These diseases are often a concern in lawns under intensive management for two reasons:

1. Improper application of certain lawn management practices, such as close mowing, can aggravate disease development.
2. When a lawn receives significant inputs of fertilizer and irrigation and frequent mowing, the homeowner or landscape manager usually has high aesthetic expectations and tolerates …

Guide For Control Of Annual And Perennial Flower And Ground Cover Diseases In The Landscape, John R. Hartman, Mary L. Witt

Agriculture and Natural Resources Publications

Herbaceous flowering plants are an asset to almost any landscape. Healthy plants are essential to maintaining a desirable aesthetic appearance. This publication suggests ways to control important infectious diseases of flowers and ground covers commonly grown in Kentucky.

Twig, Branch, And Stem Diseases Of Pine, John R. Hartman

Agriculture and Natural Resources Publications

Tip Blight

Tip blight, caused by the fungus Sphaeropsis sapinea (formerly Diplodia pinea), is a serious disease of mature Austrian, Scots (Scotch), and Mugo pines in Kentucky. In the landscape, tip blight is normally not observed until pines reach about 12 years old and begin to bear cones. Severe infections year after year can greatly weaken and eventually kill affected pines.

Apple Scab, John R. Hartman

Agriculture and Natural Resources Publications

Apple scab is the most consistently serious disease of apples and flowering crabapples in Kentucky. The most noticeable losses result from the reduced quality or premature dropping of infected fruit, but the disease also causes a general weakening of the tree when infected leaves are shed prematurely. For flowering crabapples, summer defoliation from scab invariably results in fewer flowers the next spring. The best control of scab is provided by use of scab-immune cultivars. A good spray program also can provide excellent control of apple scab, but failure to follow such a program can lead to substantial losses on susceptible …

Verticillium Wilt Of Woody Ornamentals, John Hartman

Agriculture and Natural Resources Publications

Verticillium wilt is a common problem on maple, catalpa, golden-rain tree, redbud, and tulip poplar trees in Kentucky. In addition, this disease occurs on ash, azalea, barberry, brambles, buckeye, cherry and other stone fruits, Kentucky coffee tree, cork tree, currant, elm, honeysuckle, horse chestnut, lilac, black locust, magnolia, nandina, Russian olive, osage orange, Japanese pagoda tree, persimmon, privet, rose, sassafras, serviceberry, smoke tree, sumac, tree-of-heaven, tupelo, viburnum, weigela, and yellowwood. More than 300 other woody and herbaceous plant species are known to be susceptible to Verticillium wilt.

Gray Leaf Spot Of Corn, Paul Vincelli, Donald E. Hershman

Agriculture and Natural Resources Publications

Gray leaf spot of corn, while of little consequence in the US before 1970, has become a major concern to many corn producers in recent years. Serious outbreaks of the disease first occurred in the early to mid 1970s in low-lying areas in the mountainous regions of Kentucky, North Carolina, Tennessee and Virginia. Since this time, the disease has spread to most corn-producing areas of western Kentucky and parts of Delaware, Illinois, Indiana, Iowa, Maryland, Missouri, Ohio, Pennsylvania and west Tennessee.

Fundamental Principles Of Plant Pathology For Agricultural Producers, Paul C. Vincelli

Agriculture and Natural Resources Publications

All crop plants produced in Kentucky have the potential to become diseased under certain conditions. Diseases of crops can affect yield and/or quality of the harvested commodity. This can impact profitability and increase the risks of farming.

A plant is diseased when it is affected by some agent that interferes with its normal development. Some disorders are caused by noninfectious factors, such as temperature extremes or nutrient deficiencies. However, this publication focuses on diseases caused by infectious microorganisms.

Diseased plants exhibit a variety of symptoms. These can include stunting, yellowing, wilting, twisting, reddening, browning, blighting, root rot, fruit rot, …

Kentucky Plant Disease Management Guide For Soybeans, Donald E. Hershman

Agriculture and Natural Resources Publications

This guide contains information on the biology and management of the most important diseases of soybeans in Kentucky. Fundamental information on symptoms, disease cycle, and management is provided. For some diseases, more extensive information on biology and management is also available in other Extension publications. Additional sources of information are listed under individual diseases.

Disease management in soybeans relies heavily on using disease-resistant varieties, when available, and employing sound agronomic practices. It is important to integrate both of these strategies into a comprehensive disease management program. Failure to consider one or the other will compromise the success of your efforts. …

Kentucky Plant Disease Management Guide For Small Grains, Donald E. Hershman, Paul C. Vincelli

Agriculture and Natural Resources Publications

This guide contains information on the biology and management of the most important diseases of small grains (wheat and barley) in Kentucky. Fundamental information on symptoms, disease cycle, and management is provided. For some diseases, more extensive information on biology and management is also available in other Extension publications. Additional sources of information are listed under individual diseases.

Disease management in small grains relies heavily on using disease-resistant varieties and employing sound agronomic practices. It is important to integrate both of these strategies into a comprehensive disease management program. Failure to consider one or the other will compromise the success …

Kentucky Plant Disease Management Guide For Forage Legumes, Paul C. Vincelli

Agriculture and Natural Resources Publications

This guide contains information on the biology and management of the most important diseases of forage legumes in Kentucky. Fundamental information on symptoms, disease cycle, and management is provided. For some diseases, more extensive information on biology and management is also available in other Extension publications. Additional sources of information are listed under individual diseases.

Disease management in forage legumes relies heavily on using disease-resistant varieties and employing sound agronomic practices. It is important to integrate both of these strategies into a comprehensive disease management program. Failure to consider one or the other will compromise the success of your efforts. …

Kentucky Plant Disease Management Guide For Corn And Sorghum, Paul C. Vincelli, Donald E. Hershman

Agriculture and Natural Resources Publications

This guide contains information on the biology and management of the most important diseases of corn and sorghum in Kentucky. Fundamental information on symptoms, disease cycle, and management is provided. For some diseases, more extensive information on biology and management is also available in other Extension publications. Additional sources of information are listed under individual diseases.

Disease management in corn and sorghum relies heavily on using disease-resistant hybrids and employing sound agronomic practices. It is important to integrate both of these strategies into a comprehensive disease management program. Failure to consider one or the other will compromise the success of …

Shade Tree Decline And Related Problems, John Hartman, Mary L. Witt

Agriculture and Natural Resources Publications

Shade tree decline is a complex disease situation since the cause frequently cannot be traced to one single factor. Typically, one or more primary stresses cause the health of a tree to deteriorate, and then secondary pathogens and/or insects contribute to further decline. Determining causes of decline requires careful examination of the tree and growing site as well as knowledge of the tree's history. Even then, diagnosis may be difficult because the original stress may be obscure or no longer present. Trees most commonly affected in Kentucky are Norway and sugar maples, ash and oaks (particularly pin oaks).

Managing Diseases Of Alfalfa, Paul C. Vincelli, Garry D. Lacefield, Jimmy C. Henning

Agriculture and Natural Resources Publications

Alfalfa can be a vigorous and productive forage crop for Kentucky farmers. Like all farm crops, however, alfalfa is subject to infectious diseases that can limit forage production. Managing these diseases is an important part of economical alfalfa production.

Alfalfa diseases can cause reduced forage yield, reduced forage quality, and decreased stand persistence. Sometimes, the effects of infectious diseases can be dramatic, such as sudden stand loss in a fall-seeded crop caused by Sclerotinia crown and stem rot. Often, the effects of diseases on alfalfa are more subtle but no less important. For example, alfalfa plants with Phytophthora root rot …

Submitting Plant Specimens For Disease Diagnosis, B. C. Eshenaur, Paul R. Bachi, William C. Nesmith, John R. Hartman, Donald E. Hershman, Paul C. Vincelli, Cheryl A. Kaiser

Agriculture and Natural Resources Publications

Accurate diagnosis of a plant disease depends on having a fresh sample representative of the problem. To get an accurate diagnosis when your plant has a disease problem, you need to collect the right kind of sample.

You also need to provide complete information about the plant and its history. Since the county Extension agent and the person making a diagnosis probably won't see the problem first hand at the growing site, you need to help them create a mental picture of the disease situation. You can provide this help by filling out the information requested on various Plant Disease …

Disease Management In The Home Lawn, Paul C. Vincelli, A. J. Powell Jr.

Agriculture and Natural Resources Publications

Numerous infectious diseases can occur on lawns in Kentucky. Unless diagnosed and managed, these diseases can sometimes cause extensive damage. A sound disease management program benefits your lawn in two ways:

• reduces the severity of lawn diseases
• improves the lawn's recovery should a disease outbreak occur.

This publication describes lawn management practices that can help control diseases of turfgrasses commonly used in home lawns -- Kentucky bluegrass, tall fescue, and perennial ryegrass. You can control diseases of turfgrasses most effectively by using as many of the following lawn management practices as feasible.

The first step in improving your lawn is …

Gray Mold Of Strawberry, John R. Hartman, Donald E. Hershman

Agriculture and Natural Resources Publications

Several fungi can cause developing and ripe strawberries to rot. In Kentucky the most common and economically important of these diseases is gray mold, caused by the fungus Botrytis cinerea. Also called Botrytis rot or ash mold, it is an ever-present threat to strawberries both in the field and after harvest. It can be particularly devastating because the disease strikes after investments in the crop have been made, but before returns have been fully realized.

Black Root Rot In Tobacco, Jones H. Smiley, William C. Nesmith, Gary K. Palmer

Agriculture and Natural Resources Publications

Black root rot is an important disease of tobacco in Kentucky, causing estimated annual losses in excess of $6,000,000. It rarely causes spectacular damage in any one burley field since the recommended burley varieties have some degree of resistance to the causal fungus. However, in dark tobacco plantings damage may be extensive, especially where susceptible varieties are still planted. Still, the inability to see widespread damage from black root rot is misleading. A 5% yield reduction results in a high dollar loss because the acre value of the crop is great. In addition to the reduction in yield, a lower …

Bacterial Spot Of Pepper And Tomato, William C. Nesmith, John R. Hartman

Agriculture and Natural Resources Publications

Bacterial spot can result in severe damage to sweet pepper, tomato or pimento crops to the extent that it is a limiting factor to successful production. The bacterium (Xanthomonas vesicatoria) attacks leaves, fruits and stems causing blemishes on these plant parts. Outbreaks of leaf spotting have resulted in leaf drop and poor fruit set in the field. The defoliation from leaf spotting can increase the incidence of sun scald on the fruit. Badly spotted fruit is of little value. Injury from this disease allows secondary fruit rotting organisms to get into the fruits, causing further damage.

Blackleg And Soft Rot Disease Of Potato, John R. Hartman, William C. Nesmith

Agriculture and Natural Resources Publications

Blackleg and soft rot are bacterial diseases that, in some years, causes heavy losses in Kentucky potato patches. They may cause missing hills when it destroys the seed piece or the sprouts before they emerge from the ground. The bacteria can also cause serious rotting of tubers in the hill and in storage.

Leaf Rust Of Wheat, Donald E. Hershman

Agriculture and Natural Resources Publications

Leaf rust of wheat, caused by the fungus Puccini recondita f. sp. tritici, can cause heavy yield losses in wheat. Growers frequently underestimate the losses caused by leaf rust because the disease never destroys an entire crop in Kentucky and seldom causes severe shriveling of the grain. Yet the disease reduces the number of Kernels per head, as well as grain test weight. Grain from severely rusted plants is also lower in protein content.

Some leaf rust occurs in the state every year, but variations in the weather and the amount of rust overwintering in the southern states produce …

Corn Stalk Rots, Paul Vincelli, Donald E. Hershman

Agriculture and Natural Resources Publications

Stalk rots are the most common diseases of dent corn in Kentucky. It is estimated that these diseases reduce annual yields by a minimum of 3 percent. In certain years, yield losses may reach 10 to 20 percent. Losses are due to (1) premature plant death which results in poor filling of ears or light test weights for the grain, and (2) harvest losses associated with stalk breakage or lodging. Furthermore, problems with ear rot are usually greater where lodging occurs, particularly when the harvest season is wet.

Root Knot Nematode In Gardens And Commercial Vegetables, John R. Hartman, William C. Nesmith

Agriculture and Natural Resources Publications

The root knot nematode (Meloidogyne spp.) causes damage by its feeding and reproduction on plant roots. There are several pathogenic species of this nematode but the two most commonly found in Kentucky are the southern root knot nematode, M. incognita and the northern root knot, M. hapla. These nematodes can attack numerous plants including vegetables, fruits, field crops, ornamentals and common weeds. Frequently, Meloidogyne interacts with other plant pathogens to form a disease complex in which the resulting disease is much more severe than that caused by either component alone. These nematodes are particularly serious when high populations …

Tomato Wilt Problems, William C. Nesmith, John Hartman

Agriculture and Natural Resources Publications

Fusarium oxysporum f. sp. lycopersici and Verticillium albo-atrum are two fungi that cause similar wilt diseases in tomato. Fusarium is more common in replant fields and gardens while Verticillium has been destructive on greenhouse tomatoes and in commerical stake tomatoes. Verticillium wilt is more of a problem at cooler temperatures while Fusarium wilt is considered a warm temperature disease. Both are favored by wet conditions.

Bean Diseases, William C. Nesmith, John Hartman

Agriculture and Natural Resources Publications

Viruses can cause serious damage to Kentucky bean plantings. More than one virus is often involved but bean yellow mosaic virus (BYMV) seems to be most frequently observed.