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Management of Bleeding Canker of Chestnut is not definitive and treatments are currently being investigated. Because the pathogen can be spread by contaminated tools, cultural practices are important to management. Tools should be cleaned and used with caution after being used on infected trees. Recovery of trees is possible, so management strategies are focused on keeping trees healthy so they can recover. One recommendation is to add fertilizer that contains Potassium phosphate. Soil de-compaction, providing good drainage, and mulching to minimize fluctuation of soil temperature and moisture are all ways to improve or maintain tree health and to manage the pathogen.
Chemical methods can be used to help the tree maintain health and avoid progress of the disease. Management strategies are currently being developed. A study performed in 2015 examined the infection on trees and found that 41 F1 progeny parent tree source had the most promising lines of viability for resistance.
Bacterial leaf streak of wheat is not easily prevented, but can be controlled with clean seed and resistance. Some foliar products, such as pesticides and antibiotic compounds, have been tested for effectiveness, but have proven to have insignificant outcomes on the bacterial pathogen.
Using clean seed, with little infection, has yielded effective results for researchers and producers. The pathogen, being seed-borne, can be controlled with the elimination of contaminated seed, however, clean seed is not always a sure solution. Because the pathogen may still live in the soil, the use of clean seed is only effective if both the soil and seed are free of the pathogen. Currently, there are no successful seed treatments available for producers to apply to wheat seed for the pathogen.
Variety resistance is another option for control of the disease. Using cultivars such as Blade, Cromwell, Faller, Howard or Knudson, which are resistant to BLS may reduce the impact of the disease and potentially break the disease cycle. Avoiding susceptible cultivars such as Hat Trick, Kelby, and Samson may also reduce the presence of the disease and reduce the amount of bacterial residue in the soil. Using integrated pest management techniques such as tillage to turn over the soil and bury the infection as well as rotating crops may assist with disease management, but are not a definitive control methods. Depending on conditions, the bacteria may survive for up to 81 months. Because the bacteria is moisture driven, irrigation may also increase the risks of BLS infection.
General biocides such as copper, Junction, or ZeroTol offer a potential solution to bacterial wilt of turf grass, however such chemical control ages must be applied after every mowing which may be economically impractical and ultimately phytotoxic. If bacterial wilt is present of the golf course, the best option may be to designate a mower for use on infected greens only in order to prevent the spread of the pathogen to other greens. Other viable methods include simply limiting the number of wounds the plant incurs, thereby limiting entry sites for the pathogen. A simple example would be less frequent mowing. It has also been proven that the disease is most devastating in grass cut to a length of between 1/8 and 3/16 of an inch, but less so in grass over 1/4 of an inch in length or longer, which presents an additional argument for limiting mowing. Another example is limiting sand topdressing as this is also a very abrasive technique which can create small wounds which allow entry of bacteria into the plant.
A major factor complicating the control of Xanthomonas campestris pv. graminis is weather. While it is not possible to control the weather per se, a study found great decreases in pathogen efficacy at temperatures below 20 °C, suggesting that cooling measures may be effective in combating this pathogen.
Ideally, resistant strains of the host plant should be used to control such a plant pathogen, however no resistant cultivars of turf grass have been identified to date. While no completely resistant cultivars exist, golf course owners can find solace in the fact that certain cultivars such as Penncross and Penneagle are more resistant to bacterial wilt and may thus reduce the need for frequent chemical applications and other cultural controls. Researchers are making gains towards the identification of resistant cultivars as evidenced by the finding that variation in genetic linkage groups 1, 4, and 6 accounted for over 43% of resistance among Italian rye grass.
A 1987 study found evidence of a possible biocontrol strategy for bacterial wilt of turf grass. The researchers found that antiserum to Pseudomonas fluorescens or Erwinia herbicola from hosts which have survived infections by the corresponding pathogens is capable of reducing wilt symptoms in turf grass caused by Xanthomonas campestris pv. graminis. The researchers did note, however, that while it is important to ensure the presence of a higher number of competing bacterial cells in order to reduce symptoms, one should take care to avoid over-infecting the host with a new bacterial pathogen.
Further gains towards host resistance were made in 2001 when researchers found that inoculation of meadow fescue during breeding with a single aggressive strain of the bacterial wilt pathogen greatly increased resistance in offspring, thereby demonstrating the potential of selective breeding to reduce bacterial wilt pathogenesis on turf and rye grasses.
Genetic resistance is the preferred disease management strategy because it allows farmers to minimize chemical intervention. Less pesticide and fungicide can encourage biological control agents, reduce production costs, and minimize the chemical residues in fruit. Some genetic varieties of raspberry are better than others for the control of leaf spot. Nova and Jewel Black are both resistant varieties, while Prelude and Honey Queen Golden Raspberry have some resistance, but can be susceptible depending on environmental conditions. Reiville, Canby, Encore and Anne are the most susceptible varieties.
Cultural practices are also important for the management of Raspberry Leaf Spot. Sanitation, which includes the removal of all plant debris and infected canes in the fall, reduces places for the pathogen to overwinter. Pruning the raspberry plants and planting in rows will allow for airflow to dry leaves, creating an uninviting environment for fungi. Furthermore, air flow circulation is important for reducing sporulation and successful infection. Lastly, avoid wounding the plants, as this may provide the fungus with an opportunity to infect.
This disease is hard to control because plants can carry the pathogen prior to showing any symptoms. It is important to be aware of where new plants are being planted so that they aren't exposed to disease.
The most effective method to avoid disease is to plant resistant cultivars that are specific to the location of planting. Some examples of resistant cultivars include Allstar, Cardinal, Delite, Honeoye, Jewel and Tennessee Beauty. Examples of susceptible cultivars that should be avoided include Sparkle, Sunrise, Raritan and Catskill.
Amongst the many different management strategies, cultural control practices play a significant role in prevention or reduction of disease. Some common cultural practices that have been used are as follows. In order to have more successful yields, strawberry plants should be planted in well-drained soil, in an area exposed to lots of available sunlight and air circulation. Presence of weeds may reduce air circulation for strawberry plants and create a shaded, moist environment, which would make the plants more wet and susceptible to disease. Therefore, weed growth needs to be prevented, either by chemical or cultural control methods. Immediately after harvest, any severely infected plants and plant debris should be raked, removed and burned completely to get rid of any remaining spores and reduce inoculum of the pathogen.
At the beginning of renovation, which occurs after harvest, one application of nitrogen fertilizers should be applied to help with canopy regrowth. About 4–6 weeks later, it is generally a good time to apply another application of nitrogen fertilization to the developing strawberry plants. This will allow for the plants to absorb nutrients provided by the fertilizer. However, applying too much nitrogen fertilizer throughout the spring, may result in an abundance of young foliage tissues that could be susceptible to disease.
Fungicides are not necessarily required, however if the strawberry grower decides to use fungicides, they should be applied during early in the spring and immediately after renovation. A fungicide spray schedule may also be put into place. It is recommended to spray in intervals of about 2 weeks. Examples of some recommended fungicides are Bulletin 506-B2, Midwest Commercial Small Fruit and Grape Spray Guide for commercial growers and Bulletin 780, Controlling Disease and Insects in Home Fruit Plantings for backyard home growers.
There is no resistance to Citrus Black Spot and once a tree has been infected there is no known cure causing tree removal to be the best option. Both Federal and State governments have recommended the following preventative measures.
To control "Guignardia citriparpa" fungicides like copper and/or strobilurins should be applied monthly from early May to the middle of September (in the northern hemisphere). Applications of the fungicides are recommended in early April (northern hemisphere) if that month has experienced more rainfall than usual resulting in the ideal conditions for citrus black spot to form.
Table 1. Recommended Chemical Controls for Citrus Black Spot
1)Lower rates can be used on smaller trees. Do not use less than minimum label rate.
2)Mode of action class for citrus pesticides from the Fungicide Resistance Action Committee (FRAC) 20111. Refer to ENY-624, "Pesticide Resistance and Resistance Management," in the 2012 Florida Citrus Pest Management Guide for more details.
3)Do not use more than 4 applications of strobilurin fungicides/season. Do not make more than 2 sequential applications of strobilurin fungicides.
Another method of control is to accelerate the leaf litter decomposition under the trees in citrus groves. Accelerating this decomposition reduces the chance for ascospore inoculation which generally takes place in the middle of March. There are three possible methods to hasten this decomposition. One method is the increase the mircrosprinkler irrigation in the grove to half an hour for at least five days of the week. This form of control should continue for about a month and a half. The second method is to apply urea or ammonium to the leaf litter. The last and final method to accelerate leaf decomposition is to apply lime or calcium carbonate to the litter. Urea, lime, and calcium carbonate reduce the number of fungal structures and spore production. Since the fungus requires wet conditions to thrive, air flow in the citrus grove should be maximized to reduce leaf wetness.
Along with these methods it is also important to get rid of debris such as fallen fruit or twigs in a manner that reduces the chances of infecting other plants. Citrus Black Spot can colonize and reproduce on dead twigs. To dispose of citrus debris it should either be heated to a minimum of 180℉ for two hours, incinerated, buried in a landfill, or fed to livestock. Plant trash should be moved with caution if at all to avoid spreading the infectious ascospores. Any trees that are infected with citrus black spot should be removed from the grove and disposed of. These trees must be removed because those that are declining and stressed will often have off season bloom. If there is more than one age of fruit present on the tree, it is possible for the asexual spores on the fruit to be transferred to new fruit, intensifying the disease. This off season blooming is often more problematic with Valencia oranges when old and new crops overlap.
The amount of initial inoculum will be reduced when a crop other than corn is planted for ≥2 years in that given area; meanwhile proper tillage methods are carried out. Clean plowing and 1-year crop rotation in the absence of corn allows for greater reductions of the disease as well. Note that conventional tilling can reduce disease but can lead to greater soil erosion.
http://www.lawnandmower.com/red-thread-disease.aspx
http://www.grassclippings.co.uk/RedThread.pdf
Certain techniques can be used to determine which pathogen is causing disease. One standard technique for distinguishing strains is microscopy. Under a microscope, "M. pinodes" can be diagnosed by the presence of pseudothecia. "P pinodella" can be diagnosed by the size of conidia produced. "P. pinodella" produces conidia that are smaller than the conidia of "M. pinodes" or "A. pisi". "A. pisi" can be diagnosed by the color of the conidia. In comparison to the light colored, buff spore masses of "M. pinodes" and "P. pinodella" produced on oatmeal agar, "A. pisi" spores masses are carrot red.
Other techniques for diagnosis involve serological assays, isoenzyme analysis, restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNA (RAPD) assays, and by using monoclonal antibodies.
The first strategy of management is the cultural practices for reducing the disease. It includes adequating row and plant spacing that promote better air circulation through the canopy reducing the humidity; preventing excessive nitrogen on fertilization since nitrogen out of balance enhances foliage disease development; keeping the relatively humidity below 85% (suitable on greenhouse), promote air circulation inside the greenhouse, early planting might to reduce the disease severity and seed treatment with hot water (25 minutes at 122 °F or 50 °C).
The most proficient and economical method to reduce yield losses from corn grey leaf spot is by introducing resistant plant varieties. In places where leaf spot occur, these crops can ultimately grow and still be resistant to the disease. Although the disease is not completely eliminated and resistant varieties show disease symptoms, at the end of the growing season, the disease is not as effective in reducing crop yield. SC 407 have been proven to be common corn variety that are resistant to grey leaf spot. If grey leaf spot infection is high, this variety may require fungicide application to achieve full potential. Susceptible varieties should not be planted in previously infected areas (see high risk table).
The second strategy of management is the sanitization control in order to reduce the primary inoculum. Remove and destroy (burn) all plants debris after the harvest, scout for disease and rogue infected plants as soon as detected and steam sanitization the greenhouse between crops.
The best way to manage SDS is with a resistant variety. One issue is that most resistant varieties are only partially resistant so yield reductions may still occur. Another issue is that the plant needs resistance for SDS and SCN in order to gain true resistance because of their synergistic relationship and most varieties do not have resistance for both. Aside from resistance, the only other ways to control SDS are management practices.
These include:
- Avoid planting in cool, wet conditions
- Plant later when the soil has warmed up
- Try avoiding soil compaction as it creates wet spots in the soil that can increase plant stress and SDS infection rates
- Managing for SCN as this nematode often occurs alongside "F. virguliforme"
- Deep tillage to break up compaction and help the soil warm faster
One common management tactic used in other pathogen management plans is crop rotation. In some cases, disease severity can be reduced but most often it is not effective. This is because of chlamydospores and macroconidia as they can persist in soils for many years.
Fungicides are another common product used to control fungal pathogens. In-furrow applications and seed treatments with fungicides have some effect in decreasing disease instance but in most cases, the timing isn't right and the pathogen can still infect the plants. Foliar applications of fungicides have no effect on disease suppression for SDS because the fungi are found in the soil and mainly the roots of the plants. Most foliar fungicides do not move downward through plants, therefore having no effect on the pathogen.
Feeding the lawn with a nitrogen based fertilizer will help the grass recover and help prevent future attacks.
Red Thread can be treated using a fungicide that contains benomyl or carbendazim. The infection will rarely kill the grass, usually only affecting the blades and not the roots, and the lawn should recover in time.
References
1) Ryzin, Benjamin Van. “Red Thread.” "Wisconsin Horticulture", 23 June 2013, hort.uwex.edu/articles/red-thread/
2) Harmon, Philip, and Richard Latin. “Red Thread.” "Purdue Extension", Dec. 2009, www.extension.purdue.edu/extmedia/bp/bp-104-w.pdf.
3) “Red Thread.” "Plant Protection", NuTurf, nuturf.com.au/wp-content/uploads/sites/2/2015/09/Red-Thread-Info.pdf.
4) “Suppression of Soil-Borne Plant Diseases with Composts: A Review.” "Taylor & Francis", www.tandfonline.com/doi/abs/10.1080/09583150400015904
5) “Red Thread — Laetisaria Fuciformis.” "Red Thread (Laetisaria Fuciformis) - MSU Turf Diseases.net - Disease Identification and Information. A Resource Guide from the Dept. of Plant Pathology at Michigan State University", www.msuturfdiseases.net/details/_/red_thread_14/.
6) “Lawn and Turf-Red Thread.” "Pacific Northwest Pest Management Handbooks", OSU Extension Service - Extension and Experiment Station Communications, 4 Apr. 2017, pnwhandbooks.org/plantdisease/host-disease/lawn-turf-red-thread.
Necrotic ring spot can be managed through chemical and cultural controls. Cultural control includes the use of ammonium sulfate or other acidifying fertilizers to suppress the pathogen by lowering the pH of the soil to between 6.0 and 6.2. The more acidic soil discourages the activity of "O. korrae" (9) When reducing pH to these levels, additional manganese applications should be undertaken to compensate for lower pH. As of now, there are only two resistant cultivars of bluegrass, which are ‘Riviera’, and ‘Patriot’ (9). One component of their resistance could be that they are tolerant to low temperature, because the grass is more susceptible to the pathogen under colder temperatures(8). In addition, reducing watering inputs and growing turf on well drained soils can lessen disease symptoms.
Many different fungicides are used to control the pathogen, Fenarimol, Propiconazole, Myclobutanil, and Azoxystrobin (8). Historically, Fenarimol and Myclobutanil were predominantly used (14). In a study where diluted pesticides were sprayed throughout infested test plots, Fenarimol was found to be the most effective with a 94.6% reduction of the disease. Myclobutanil also decreased the amount of disease, but only by 37.7% (8). Myclobutanil is generally recognized as a very weakly acting demethylation inhibitor (DMI) fungicide and fenarimol is no longer registered for turf so a number of other DMI fungicides have been employed successfully, including Propiconazole, Tebuconazole, Metconazole and others. Pyraclostrobin and Fluoxastrobin have also been used to control the pathogen.
There are several ways to manage turf melting out. They include both cultural and chemical.
Thousand cankers disease can be spread by moving infected black walnut wood. Trees intended for shipment should be inspected for dieback and cankers and galleries after harvest. G. morbidia or the walnut twig beetle ("Pityophthorus juglandis") are not currently known to be moved with walnut seed . There is currently no chemical therapy or prevention available for the disease making it difficult to control the spread of the disease from the west to the eastern united states. Wood from infected trees can still be used for commercial value, but safety measures such as removing the bark, phloem, and cambium to reduce the risk of spreading the disease with shipment. Quarantines have been put in place in some states to reduce the potential movement of fungus or beetle from that region. On May 17th, 2010, the Director of the Michigan Department of Agriculture issued a quarantine from affected states to protect Michigan’s black walnut ecology and production. Contacting the appropriate entities about possible infections is important to stopping or slowing the spread of thousand cankers disease.
The bacteria can survive in the rhizosphere of other crops such as tomato, carrots, sweet potato, radish, and squash as well as weed plants like lupin and pigweed, so it is very hard to get rid of it completely. When it is known that the bacterium is present in the soil, planting resistant varieties can be the best defense against the disease. Many available beet cultivars are resistant to "Pectobacterium carotovorum" subsp. "betavasculorum", and some examples are provided in the corresponding table. A comprehensive list is maintained by the USDA on the Germplasm Resources Information Network.
Even though some genes associated with root defense response have been identified, the specific mechanism of resistance is unknown, and it is currently being researched.
Strawberry foliar nematodes are difficult to manage due to their robust life cycle. While dormant, they are quite difficult to kill, and they remain viable in dry debris for more than one year. Adult nematodes can survive desiccation and lie dormant for several years. Eggs can stay dormant until survival conditions are optimal for growth. Once eggs or nematodes are present in the soil, they are nearly impossible to eradicate because they can move laterally in the soil to escape non-optimal conditions. They are found in most foliar tissue, including the leaves, stems, buds, and crowns, making it difficult to control the disease on the plant itself once it has been infected
Many plant diseases are managed chemically, but due to a ban of nematicides there are currently no nematicides available for any type of foliar nematode. Some insecticides, pesticides, and plant product extracts from plants such as Ficus and Coffee (of which many pesticides and nematicides are neem-based ) can be used to reduce the numbers of strawberry foliar nematode (a reduction of 67-85%), but none of these chemicals can completely eradicate the nematodes once they are present in the soil. These chemicals affect all stages of the life cycle because they target the nervous system. One chemical, ZeroTol, a broad-spectrum fungicide and algaecide, was shown be to 100% potent against nematodes living in a water suspension, but the study does not show how nematodes are affected in soil or outside of a laboratory environment.
An alternative method of control is a hot water treatment, which affects all stages of the life cycle and can be used on whole plants. This treatment has been used for 60 years with some effect in greenhouse plants, but not on a widespread agricultural level. The difficulty in this treatment is that exposure times to hot water and the temperature of the water must be optimized so that the nematodes are killed, but the cultivar remains undamaged. One study, which researched five California strawberry cultivars including Chandler, Douglas, Fern, Pajaro, and Selva, demonstrated that the minimum-maximum exposure times and temperatures that killed the nematodes but did not harm the cultivars were: 20–30 minutes at 44.4⁰C, 10–15 minutes at 46.1⁰C, and 8–10 minutes at 47.7⁰. The study also found that fruit production was more sensitive to the treatment than mere survival of the plant, so the minimum exposure times are recommended when using plants for fruit production, and the maximum time is recommended when using plants for propagation.
One of the best and most practiced forms of management to reduce the local and geographical spread of the disease is sanitation. Removing the infected leaves of the plant can reduce spread in the individual plant, but because the nematode is found in most foliar tissue the nematodes may already be present in other tissues before the leaf symptoms appear. The nematodes can also move on the outside of the plant surface when water is present, so the nematodes can move around the outside surface of the plant and infect new tissues. Therefore, once plants show any signs of infection, they should be removed and destroyed. Reducing or eliminating overhead irrigation can prevent dispersal of the nematode through water splashing, and keeping the foliage dry prevents the nematodes from moving on the outside of the plant. Plants should be placed further apart to allow water to dry quickly after irrigation. In the greenhouse or nursery, soils, containers, and tools should be sterilized on a regular basis, and the floor and storage areas should be free from plant debris.
The most important form of management is prevention of introduction of the nematode to the environment. One should avoid planting infected plants, and it is recommended that new plants (especially in a personal lawn or greenhouse) be planted in an isolated area to monitor the plant for the development of symptoms before transplanting the plant near established plants. This will prevent the established plants from getting infected from a new, infected plant. All symptomatic plants should be destroyed immediately. Dead plant material should also be handled with caution. Vermiform nematodes can survive and reproduce in compost piles of dead plant material by feeding on fungi that are commonly found in compost. As a result, infected plants should be burned and sterilized to prevent the nematodes from infecting soil (which results directly from burying the material), or other plants (from allowing the plant to remain rooted in the soil near other plants as it dies).
The disease can tolerate warm or freezing temperature, but favorable conditions for the disease include wet and humid weather. Irrigated fields provide a favorable environment for the disease. The disease has become quite prevalent in semi-tropical regions, but can found all over the world where wheat is grown. Strong winds that blow soils help contribute to the spread of disease. When the spread is initiated by wind blown soil particles, symptoms will be found most readily towards the edges of the field.
Bacterial wilt of turfgrass is the only known bacterial disease of turf. The causal agent is the Gram negative bacterium Xanthomonas campestris pv. graminis. The first case of bacterial wilt of turf was reported in a cultivar of creeping bentgrass known as Toronto or C-15, which is found throughout the midwestern United States. Until the causal agent was identified in 1984, the disease was referred to simply as C-15 decline. This disease is almost exclusively found on putting greens at golf courses where extensive mowing creates wounds in the grass which the pathogen uses in order to enter the host and cause disease.
Control of Leucostoma Canker is possible through a combination of pest and crop management techniques following life cycles of the trees. The strategy is implemented following techniques aimed at reducing number of pathogenic inoculum, minimizing dead or injured tissues to prevent infection, and improving tree health to improve rapid wound healing. Chemical controls have not been very effective at controlling this disease with no fungicides registered specifically for control of "Leucostoma" spp., and demethylation-inhibiting (DMI) fungicides having almost no effect on "L. persoonii".
"F. oxysporum" is a major wilt pathogen of many economically important crop plants. It is a soil-borne pathogen, which can live in the soil for long periods of time, so rotational cropping is not a useful control method. It can also spread through infected dead plant material, so cleaning up at the end of the season is important.
One control method is to improve soil conditions because "F. oxysporum" spreads faster through soils that have high moisture and bad drainage. Other control methods include planting resistant varieties, removing infected plant tissue to prevent overwintering of the disease, using soil and systemic fungicides to eradicate the disease from the soil, flood fallowing, and using clean seeds each year. Applying fungicides depends on the field environment. It is difficult to find a biological control method because research in a greenhouse can have different effects than testing in the field. The best control method found for "F. oxysporum" is planting resistant varieties, although not all have been bred for every forma specialis.
"F. oxysporum" f. sp. "batatas" can be controlled by using clean seed, cleaning up infected leaf and plant material and breeding for resistance. Fungicides can also be used, but are not as effective as the other two because of field conditions during application. Fungicides can be used effectively by dip treating propagation material.
Different races of "F. oxysporum" f. sp. "cubense", Panama disease on banana, can be susceptible, resistant and partially resistant. It can be controlled by breeding for resistance and through eradication and quarantine of the pathogen by improving soil conditions and using clean plant material. Biological control can work using antagonists. Systemic and soil fungicides can also be used.
The main control method for "F. oxysporum" f. sp. "lycopersici", vascular wilt on tomato, is resistance. Other effective control methods are fumigating the infected soil and raising the soil pH to 6.5-7.
The most effective way to control "F. oxysporum" f. sp. "melonis" is to graft a susceptible variety of melon to a resistant root-stock. Resistant cultivars, liming the soil to change soil pH to 6-7, and reducing soil nitrogen levels also help control "F. oxysporum" f. sp. "melonis".
The fungus "Trichoderma viride" is a proven biocontrol agent to control this disease in an environment friendly way.
Golf courses affect the United States economy with about 18 billion dollars annually. Turf melting out is an important disease economically for golf course superintendents. When turfgrass quality is affected on a golf course, the course has a potential to lose golfers, in turn, losing money. After a golf course has an outbreak of turf melting out, the damage needs to be assessed and the turf needs to be replaced. Mending these damaged areas cost money from the fungicide applications to rid the area of the disease to the replacement of turf. Simple cultural controls help reduce the risk of this disease, but when the methods are not used, it can be costly.
There is no known cure for little cherry disease and tolerance breeding programs have not yielded any cultivars able to withstand the effects of the disease for more than a few seasons. Thus, prevention of spread has been the focal point in combating the disease.