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Plant Disease Management - Science topic

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Some bacteriophages of Xylella  fastidiosa, Liberibacter spp., Spiroplasma spp. could offer protection against the plant disease. Although several published experiments show some effects in reducing symptoms development, the tested control measures are not able to completely eliminate the bacteria from diseased plants. What is the future of phage-based control of tree diseases caused by these bacteria?
EFSA Panel on Plant Health (EFSA PLH Panel), Bragard C, Dehnen‐Schmutz K, Di Serio F, Gonthier P, Jacques MA, Jaques Miret JA, Justesen AF, MacLeod A, Magnusson CS, Milonas P. Effectiveness of in planta control measures for Xylella fastidiosa. Efsa Journal. 2019 May;17(5):e05666.
De Leon, Victoria S. Investigation of'Candidatus Liberibacter Asiaticus' Prophages in Texas and Florida. Diss. Texas A&M University-Kingsville, 2020.
Chipman PR, Agbandje-McKenna M, Renaudin J, Baker TS, McKenna R. Structural analysis of the Spiroplasma virus, SpV4: implications for evolutionary variation to obtain host diversity among the Microviridae. Structure. 1998 Feb 15;6(2):135-45.
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Characterization of Novel Virulent Broad-Host-Range Phages of Xylella fastidiosa and Xanthomonas
Authors: Stephen J. Ahern, Mayukh Das, Tushar Suvra Bhowmick, Ry Young, Carlos F. GonzalezAUTHORS INFO & AFFILIATIONS
Best Regard.
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In plant pathology, I think definitions of canker and anthracnose seem to resemble. Are they synonymous or is there any difference between them based upon type of causative agent, based upon area and severity of symptom or something else?
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This can be very helpful, I have copied this directly from the internet.
I owe not right for the information
Minnesota has had a wet spring. The Twin Cities have experienced a winter that seemed to drag on for longer than expected, and only reluctantly given way to a wet spring. Many people assume that an abundance of water is healthy for trees. In many cases, that assumption is true: but not always.
Sometimes an excess of water can cause bacterial and fungal tree infections to spread more. To help homeowners ensure their trees are healthy this spring, Birch Tree Care discusses two diseases that are hampered by wet springs.
Bacterial Cankers
The bacterium that causes canker, Pseudomonas syringae, penetrates trees through damaged bark or an existing wound, such as a pruning cut. Bacterial canker is found commonly on Cherries, Crabapples, and Plums. Bacterial canker infections happen during Autumn, Winter and early Spring - during cool, wet weather. The infection spreads by rain, water, and pruning tools not disinfected.
Cankers begin to form in mid-spring, and soon afterwards shoots may die back. Small holes appear on foliage from early summer.
This bacterial infection is relatively easy to spot - "gummy" lesions characteristically form on branches or trucks. In spring, when trees begin active growth, a sour-smelling sap may ooze from these troubled areas. The bacterial cankers become darker than the surrounding healthy bark, and the underlying tissue is moist and reddish-brown to black.
If the infected area circles the branch or trunk, the leaves above the diseased area turn yellow. When this happens, the growth of the branch or tree stops entirely, and the tree or branch dies.
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Birch Tree Care has over 30+ years of professional experience in tree related diagnostics. This wealth of experience allows us to share some valuable insight with you in accurately identifying and treating a bacterial canker.
Symptoms of bacterial cancers are not only present in branches and trunks but also shoots and leaves. Other signs like wilting leaves, shoot dieback and more only make bacterial cancers easier to spot.
Bacterial cankers may cause small brown spots to appear on leaves. These brown spots are usually round and fall out later, leaving leaf holes. Overall, this produces an appearance that looks as if the leaves have been hit by shotgun pellets.
Treatment
Prune flowering trees during blooming (July and August) when wounds heal fastest.
Remove wilted or dead limbs well below infected areas. Burn these branches, or take them to a landfill.
Paint the freshly cut area with wound paint to protect the tree against re-infection.
Birch Tree Care offers free quotes to customers. If you would like to have your ornamental trees expertly treated, reach out to our certified experts today.
Anthracnose
Fungi in the genus Colletotrichum cause anthracnose. Colletotrichum is a group of plant pathogens responsible for diseases on many plant species. Spores overwinter in infected twigs, branches or fallen leaves and spread through wind and rain the subsequent season.
Infected plants develop dark, water-soaked lesions on stems, leaves or fruit. The centers of these lesions frequently become covered with pink, viscous masses of spores, especially during moist, warm weather.
Common hosts include ash and oak. In ash trees, infection usually occurs in the foliage or twigs. In oak, however, the infection can happen in the twigs, shoots, leaves or buds. The optimal temperature for anthracnose to develop in ash is15-20°C and the fungus grows more rapidly with wet weather. Oak anthracnose develops most quickly when temperatures around 10 °C.
Ash leaves infected during spring become misshapen. In early infection, leaves develop brown and yellow blotches while the edges of the foliage curl and eventually fall off.
In early infection, leaves develop blotches of necrosis, while later infections produce necrotic leaf spots with a chlorotic ring. Severe infections can cause significant defoliation: eventually, larger branches may be cankered and killed. Several seasons of infection can cause trees to decline or become susceptible to other pests.
In oak, there are generally three phases of the disease; twig blight, where young branches are encircled and killed, shoot blight, where new shoots are killed during expansion, and leaf blight, where leaves become distorted and necrotic at the tips or along veins. Repeated infections of established trees rarely cause permanent damage, but younger trees may need protection.
Treatment
Remove cankered branches and prune trees. Pruning the tree increases air circulation and helps prevent moisture.
Rake and destroy fallen leaves where the fungus can overwinter.
Apply a fungicide containing Chlorothalonil.
Fungicides are toxic carcinogens and must be applied correctly. Reach out to Birch Tree Care to book tree care and expert service.
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Bio char is a type of charcoal used as a soil ameliorant for both carbon sequestration and soil health benefits and also being used for the management of soil borne plant pathogens but I doubt whether it will be an economic and ecofriendly approach for the management of plant diseases.
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Good question , could a possibility , but right now , such reports are miniscule in number....
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If I were to receive an import of a new fruit species in the country and, upon arrival, the whole lot was diseased, what steps do I take to diagnose and solve the problem? Is there a general procedure or scheme followed for post-harvest management to identify the cause of the unknown disease?
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I want to initiate work on mycorrhizal association in crop plant and its relation in plant disease management. So, i am seeking expert's help and collaboration on this research aspect.
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I suggest to use method given by Hyman (1984) or Schenck and Perez (1990). Of course, most of the methods works best on sandy soils, and less well in clay and organic soils.
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We have some incidences of infestation of Orobanche in tomtaoes in Kenya. Farmers need assistance but I am not sure of the most effective approach to dealing with it. There are indications of good sanitation and solarization for prevention but nothing on dealing with an infestation.
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Please also see the following RG link.
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Proposed Title: Biopesticide in Sustainable Agriculture for Insect-pest and Plant Diseases Management: Prospective Future, Market Trends and Opportunities
CONTENT
1. INTRODUCTION
2. DEFINITION AND CONCEPT OF BIOPESTICIDES
2.1. Biopesticide
2.2.1. Concept of Biopesticides
3. CLASS OF BIOPESTICIDE FOR SUSTAINABLE AGRICULTURE
3.1. Microbial Pesticide
3.1.1. Bacterial Pesticide
3.1.2. Fungal Pesticide
3.1.2.1. Market Potential of Fungal Pesticide
3.1.3. Baculoviral Agents
3.2. Biochemical Pesticide
3.2.1. Insect Pheromones
3.2.2. Botanical Pesticides
3.2.2.2.1. Pyrethrum
3.2.2.2.1.1. Mode of Action
3.2.2.2.2. Neem
3.2.2.2.2.1. Mode of Action
3.2.2.2.3. Rotenone
3.2.2.2.3.1. Mode of Action
3.2.2.2.4. Sabadilla
3.2.2.2.4.1. Mode of Action
3.2.2.2.5. Ryania
3.2.2.2.6. Nicotine
3.2.2.2.6.1. Mode of Action
3.2.2.3. Factors Influencing to the Use of Botanical Pesticides
3.2.2.3.1. Raw Material Availability
3.2.2.3.2. Standardization of Botanical Extracts
3.2.2.3.3. Regulatory Approval Remains the Most Alarming Blockade to the Commercialization of New Botanical Insecticides
3.2.2.3.4. Drawbacks and Barriers to Commercialization
3.2.2.3.5. Sustainability
3.2.2.4. Market Opportunities for Botanical Pesticides
3.2.2.5. Merits and Demerits of Botanical Pesticides
3.2.2.5.1. Merits
3.2.2.5.2. Demerits
3.2.3. Insect Growth Regulators (IGRs)
3.2.3.1. Chitin Synthesis Inhibitors (CSIs)
3.2.3.2. Juvenile Hormone (JH) Analogs and Mimics
4. ADVANTAGES OF BIOPESTICIDES
5. APPLICATION METHOD
6. POTENTIAL OF BIOPESTICIDES AND PROSPECTIVE FUTURE
7. MARKET TRENDS OF BIOPESTICIDE IN NATIONAL AND INTERNATIONAL TRADE
8. OPPORTUNITIES AND CHALLENGES IN SUSTAINABLE AGRICULTURE
9. CONCLUSION
10. SUMMERY
GLOSSARY FOR TECHNICAL TERMS
REFERENCES
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Insect-pest and Plant Diseases Management with biopesticides: Prospective Future, Market Trends and Opportunities.
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Dear friends
Upward curling symptoms were observed in the matured leaves of papaya seedlings transplanted in the field. As per our observation it is not a virus. What may be the reason for this kind of curling?
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Please give me solution of these problems in papaya
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Hi all dear professores
as you see all sepals have been changed to large leafs. Please notice that these symptoms just have seen on 3 bushes. What is your idea about this problem?
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symptoms of phytoplasma
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Pomegranate trees, fruits, leaves, stems, all parts are spoiled, due to bacterial blight, and checked it is xanthomonas axonopodis, what will the permanent solution or treatment be?
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IIHR Bengaluru has succeeded in control of bacterial blight oof pomegranate through microbial interventions. We have developed a consortium of microbs which supresses the disease, promote plant growth and mobilizes nutrients through which the plant develops internal resistance to meet the challanges of Xanthomonas axonopodis pv. punicae. This has been extensively tried and demonstrated successfully in Karnataka. Today this product named Arka Microbial Consortium (AMC) is licenced and is made available to farmers.
You can watch this youtube videos on this control measure
Arka Microbial Consortium for the Control of Pomegranate Blight ...
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Traditionally farmers in many African nations (and elsewhere) still grow individual crops not only in inter- specific (different species), but also in intra-specific (same species) mixtures. However, the development ideology to improve production has been one promoting displacement of these with new 'improved' varieties or hybrids with often questionable medium to longer term results. We now know better the value of useful diversity to maintain crop robustness agains biotic and abiotic stress.
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through IPM and IDM
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Dear colleagues & friends,
I am in search of alternative and environment friendly ways to control (manage) Hessian fly (Cecidomlye) in wheat without the use of insecticides.
Hessian fly is causing a lot of damage to wheat in Morocco. Its negative impact on yield is devastating during dry years.
Please share your experience and/or publications on this topic.
Thank you for your collaboration.
All the best.
Nasser
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Dear Al-Ani,
I really appreciated your kindness for sharing these many interesting books and other documents.
Kind regards.
Si Bennasser
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While growing several varieties of Cucurbits, I encountered this type of yellowing in some of the varieties. It started two weeks after transplanting an organic field. I have already ruled out herbicide damage. The yellowing starts from the center of the leaf and spreads out. It is also present on young emerging leaves. As the plants grew, the yellowing appears to reduce/disappear, and so I believe it may not be a nutrient deficiency. See photos below. Any ideas? 
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Can you please add some information about soils also.. to help identify the problem precisely...
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As you may know, cultivation of transgenic plants is prohibited in some countries. In other hand, the major plants in brassicaceae family have erucic acid in their seed oil. Then how we can produce a brassicaceae plant with 00 or 000 erucic acid without genetic engineering technology?
Canola (the erucic acid - free rapeseed)  is cultivated in over the world. Are this plans NON_GM? If yes, hoe they have been produced?
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By the way, from this web link (http://livewell.jillianmichaels.com/canola-oil-compared-olive-oil-5365.html), it indicates "Canola oil must meet specific regulations regarding erucic acid a glucosinolate content, with no more than 2 percent erucic acid and 30 micromoles per gram of glucosinolates." So, I guess today's canola oil probably is not erucic acid zero, but only low in amount. But, as Rahul Kumar has mentioned, with known biosynthesis pathway, and genes controlling this pathway, one can use CRISPR to knock out these genes and get erucis acid-free (zero) plants.
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Some were told - 2,4 D damage, in the Google also I am getting same images but it is slightly spreading (a farmer observed this)
Any other reason... 
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Hi 
its look like Herbicides injury , maybe 2-4 D
Best Regard
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I have some problems with Acacia mangium seedlings sown in nursery. The tip leaves was subjected to severe chlorosis as in pictures attached. Do any of you know this symptoms and any suggestions/ideas for a solution is much appreciated.
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Dear Kien
There is many dark spot on leaves its look like Bacterial or fungal infection so the chlorosis may be due to toxin produced by the causal agent of the dark spot
Best Regard
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we want to test cell wall component of Chaetomium globosum such as chitin for their ability to induce SAR in Tomato plant against leaf spot disease.
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Thank you Dr Rekha
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What type of defenses do plants have against parasites
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I search this information for a study of this disease in Submédio do Vale do  São Francisco , Pernambuco, Brazil.
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Generally oats infected with barley yellow dwarf virus show reddish colouration of leaves whereas leaves of rice infected with the same virus become yellow in colour. what is the reason and mechanism behind this
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Good Luck
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Phytoplasmas are specialised bacteria that are obligate parasites of plant phloem tissue. Phytoplasma infection is transmitted through sap-sucking insects and grafting. Is it possible to store the phytoplasma for long term and re-culture whenever required?  
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Wongwarat has proposed some methods which will be of significance to you.
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My Capsicum plants are around 20-30 days old and they are loaded with some kind of insect with a white powdry mass surrounding them. The insects are mostly restricted to both the surfaces of the leaves plus the pedicel of the flower and other floral parts?
Can any one help identify this and suggest the remedial measures?
Thanks
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You have problems with black aphids and white flies.
Many of the insecticides used to control other pepper insect pests can contribute to rapid increases of aphids and whiteflies. Natural enemies such as lady beetles, parasitoids (Aphidus, Aphelinus, Encarsia, Amitus etc) green lacewings, damsel bugs, and hover fly larvae usually control aphids and whitefly populations adequately. Broad spectrum insecticides, particularly pyrethroid insecticides, can delete these natural enemies and allow aphid populations to develop unchecked. Insecticides should only be applied for other insects when necessary, as determined by trap catches and scouting, and care should be taken to select insecticides that do not favor secondary aphid problems. 
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Wilt disease of Acacia plantation.
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Thanks so much for knowledge sharing. N should be one of the focus nutrients.
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Hi,
I would like to know more about how can I enable disease/pest infestation forecast with the help of drone image analysis. 
Any input will be a great help.
Regards,
Manoj
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Hello Gupta,
Firstly, you need to know the environment and weather condition of your region, and the optimum circumstances required to show the outbreak of the pest. Moreover, studying or make a review about the ability of previous pest infection in your region is an excellent option to expect the infection time.  Also, field review before plantation and applying for protection methods e.g. (weed control, soil Stirring, dispose of previous crop residue, ...etc)  considered as a great options to prevent the pest  development and find a solution before outbreaking. 
Finally, all of these are simple content it can help you to find the right protection for your plants.
Best luck,
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Orchard of walnut trees  with system of drip irrigation of North Patagonia, Argentina,. The trees show symptoms in leaves as is observed in the photo.
Thanks!
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Dear Maria 
At first you should culture the symptomatic parts of leaves in the PDA medium and Nutrient agar medium. Then you will be able to confirm whether this disease caused by fungi or bacteria. Actually it may be caused by deficiency of nutrients. 
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Wheat blast caused by Magnaporthe oryzae Triticum pathotype is a fearsome disease first emerged in Bangladesh. It poses serious threat to food and nutritional security of Bangladesh. Scientist fears that this disease may spread to neighbouring Asian countries. We need to isolate the pathogen in infected plants and alternate hosts and thus needs a cheaper and faster protocol.
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Hi: You can use water agar (WA) to isolate the pathogen from the tissue after surfers sterilize, WA allows the pathogen to grow very slowly that give you time to purify it in new culture
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Dear all 
I received this picture from melons farmer.  I wanna know what the cause of these symptoms on the leafs is? Based on data from farmer these symptom has been seen around 40% of plants and they have been extended Gradually.
would you please tell me that it is related to leaf spot or phytotoxity and if this is leaf spot, what kind of fungi? 
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Distribution of lesions on the leaf looks like chemical burn. 
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metabolic demands of fever vs the natural response to infection.
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Fever should be treated only when it is higher than 41 celcius, or when it is causing symptomatic disturbance to the patient like diaphoresis, anxiety, tachypnea, tachycardia and/or hypotension. However we use antipyretics only as needed, not in a long term basis as fever is an important sign to follow the response to treatment or to identify the presence of a new infection or resistance to treatment. 
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I have several ryegrass cultivars infected with (E+) and without endophyte (E-)under two water regimes. If I detect an main effect of endophyte on the plant yield but not an interaction between endophyte and water regimes, will one say endophyte has an effect on drought tolerance of the host?
I found in the published research that when people say endophyte infection improved drought tolerance, it refers to there is no difference between E+ and E- plants under irrigated conditions but E+ improved yield or other physiological traits compared to E- plants under drought. However, if endophyte infection improved yield or other physiological traits under both irrigated and non-irrigated conditions, will one still consider endophyte infection improves the drought tolerance of the host?
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Dear Lulu,
To answer your first question : If you have significant effect of an endophyte on plant yield, and no interaction between endophyte and water regimes, you can look at the main factor effects, in your example improvement in yields of the plants grown under stress conditions is due to endophyte inoculation (or simply put, plants grown under stress and inoculated with endophyte had significantly higher yield compared to un-inoculated control plants.)
the second question: if an endophyte infection improved yield or other physiological traits under both irrigated and non-irrigated conditions, will one still consider endophyte infection improves the drought tolerance of the host? Yes, it is common that plants infected with endophytes  overall perform better, both under optimal and stress conditions.
best,
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Hi
would someone please tell me what is the cause of these problems on tomato?
kindly notice that the flowers of tomato have  withered and dries. these tomato was planted in open field. 
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This symptom showed phosphorus deficiency because violet colour leaves showed.
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There are reports of PBW survival in bollgard II Bt cotton hybrids in India. Will it be a potential problems in years to come? How to over come.
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All plant breeding results into resistance against targeted pests, sooner or later. Fact is that with Bt crops the reaction will be easier and quicker and up to now it is not really a big concern. Hope you have the publications of  Bruce Tabashnik, if not, just come back, cheers, Klaus
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Any idea about using charcoal in plant disease resistance or control in lab or field work.
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Dear Oadi Matny,
I have received an information from my colleague about attached article  "Induction of Systemic Resistance in Plants by Biochar, a Soil-Applied Carbon Sequestering Agent"
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These look-alike proliferation tumors slough off on the most magnified photo in the group (1st photo in the group, right side). The tree host species is red oak Quercus rubra.
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Symptoms on oak infected by Pezicula cinnamomea.
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Would you tell me the needed amount of inoulum for stripe rust epidemics;
1. for adult plant test in the field under natural conditions,
2. for adult plant test in the green house,
3. for seedling test in the greenhouse.
Exact amounts please.
Thank you.
Nusret
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 Below the conditions we have been using successfully at our lab. Seen the fragility of the urediospores the viability from one to another bath of spores may vary. Thus it is safe to use an excess of inoculum for mass inoculation in combination with  optimum incubation conditions. 
For field inoculations we have used inoculated plants and studied the focus expansion. See attached file
2.2. Yellow or stripe rust caused by Puccinia striiformis Westend. f. sp. tritici
2.2.1. Collection and storage
Leaves showing young lesions are collected in the field, put in paper envelopes and used directly for increase of inoculum or stored for later analysis.  Envelopes containing 4-10 rusted leaves are laid out individually on a table and then over a desiccant at room temperature (18-21°C) until the material is dry (1-2 days). The envelopes are then sealed in a polyethylene bag and stored in a refrigerator for a few weeks.  For long term storage the urediospores are collected by tapping rusted leaves over a piece of aluminium foil, transferring the spores to vials, vacuum drying them at reduced pressure (40 to 50 Torres), sealing the tubes and storage at 5-8°C.  Spores dried to 20-30% relative humidity and sealed in a glass vials can be stored in liquid nitrogen.
2.2.2.     Inoculum increase
Seeds of a yellow rust susceptible cultivar (cultivar showing severe epidemics in the area from where diseased samples were collected) are grown in 8-10 cm Ø pots, 20-30 seeds/pot) in a greenhouse or growth chamber under a day/night regime of 18°C/15°C and 18/6h with a light intensity of around 20,000 lux. Seedlings are inoculated at 7 to 9 days when the primary or seedling leaf is fully expanded.  Fresh leaves with active lesions collected in the field or dried leaves stored in the refrigerator are rubbed or brushed over the pots to be inoculated in order to deposit urediospores.  Spores stored in the refrigerator or under liquid nitrogen are dusted on the leaves or suspended in distilled water with a drop of wetting agent Tween 20 per 100 ml or in mineral oil (Soltrol 170) and sprayed on the leaves. 
 The pots sprayed with a spore suspension in water are immediately transferred for 48 h in a moist chamber held at 9°C and 16 h light of intensity of about 7500 lux and 8 h dark.  The oil used for the others must first evaporate before dew application.  After infection, the plants are placed a glasshouse held at 15 + 2°C in small plastic cages 30x25x20 cm, allowing air exchange but restricting movement of urediospores.  If necessary, day length is kept at 16 h by supplementing light with fluorescent tubes or other sources giving a light intensity of 7,500 lux.  Yellow rust is often difficult to grow in late autumn and winter, due to light deficiency, which reduces sporulation intensity.  Yellow rust is also very sensitive to air pollution.
Urediospores appearing 10-14 days after inoculation are collected every 2 days, dried and then stored in glass ampoules in liquid nitrogen.
2.2.3. Mass inoculation of older plants
Trays with older plants (6-7 leaves up to flag leaf fully unfolded on main tiller) are grown in the greenhouse under a day/night regime of 18°/15°C and 18/6h with a light intensity of around 20,000 lux. Spores suspended in mineral oil or water + wetting agent (1x10 5 to 1x10 6 spores/ml) are atomised as uniformly as possible on the plants.  The trays are then enclosed single or grouped in a moist chamber (see 2.1.4.). The temperature should be kept around 9-13°C, the optimum for germination and infection.  Light intensity during the 16h day should be around 7500 lux; dark period 8h.  After 48h the moist chambers and cheesecloth shade are removed and incubation continued under a day-night regime of 18°/15°C and 16/8h with light intensity around 20,000 lux.  Temperature rises above 20°C may stop disease development.  The lesions become visible on the inoculated leaves after 2-3 weeks incubation.  Percentage of leaf area covered by lesions is scored until full expression of the inoculation (Agricultural development and advisory service Key N° 1.7.1).
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Pongamia pinnata leaves have some kind of infection on leaves, what's that?
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Leaf spots, patches, curls and partial drying can also be caused by insect damage, nutritional deficiencies or drying of leaves either due to water deficit or high temperatures associated with dry winds in tropical climates where Pongamia is grown. In case you are interested in this tree species, you may check my chapter on this plant.
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friends, mango black spot is a very economically important disease and one of my farmers is having the problem...I can give one hint that there were severe rains during the fruit development stage for a week or week and half.....I cant say that rains are the exact causes but I need a commercially applicable solution.....please help to suggest something useful for the farmer..
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ok....thank you Bhavin Sir...but how much is that remedy effective for commercial application....means is it readily suggested to farmers....are there any achievements made in any of your known places?....thanks for the precious suggestion
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I've tried growing it on a fruit, on leaves and brushing an agar plug but no success yet. I have tried putting the sporangia directly on tomato leaves, fruits but they rot before any P. infestans grows?
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Be aware that potato races may be (usually are) less virulent on tomato (and vice versa).
In an aseptic laminar flow hood, we surface sterilized tomato leaves in 10% bleach solution for 5 min, then rinsed them twice in ddH2O for 5 min each, and then inoculated them with ~20 ul droplets of zoospore/sporangia suspension at ~10^4-10^5 cells per ml. We incubated them in autoclaved plastic boxes lined with moist, sterile filter paper at 17C, and usually saw symptoms in a week or so, depending on pathogen isolate and host genotype. It is very important to maintain high humidity in the boxes, so we would wrap the edges with parafilm and/or place the entire box into large ziplock bags.
Once fluffy mycelium is visible on the leaf surfaces, you can transfer some to antibiotic plates (e.g., PARP or RVN, we used RVN) and then subculture to ensure the purity of the isolation.
A lot of these steps were necessary to maintain our pure isolates. If you just want to culture some random P. infestans, you can do the same thing with field-collected infected leaves. Just put them in a plastic bag and incubate them for a day or two until they get fuzzy, then plate the mycelium on antibiotic medium. Subculture to purify the isolate, then run PCR (or Koch's 3rd and 4th postulates) to confirm that what you isolated is actually P. infestans.
I've linked one of our pubs with detailed materials and methods. Best of luck with your inoculations!
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What is the aim? fine mapping or what?
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a colleague is interested in assessing yield penalty for groundnut cultivars having multi resistance to diseases such as leaf miner, rosette, leaf spot, and tolerant to drought
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thank you very
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Do anyone have good experience of following identified microbes and it’s by by-products used for pathogen control in plant disease management
*Agrobacterium spp.
*Bacillus spp.
*Pseudomonas spp.
*Streptomyces spp.
*Ampelomyces spp.
*Candida spp.
*Coniothyrium spp.
*Gliocladium spp.
*Trichoderma spp.
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You may be to visit http://toxnet.nlm.nih.gov/ Here are information on toxicology and antimicrobial or antagonics compounds from microbial developments. Here are one of my poblications about this questions.
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I would like to know the reason for it and if there is any cure, etc.
Thank you
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Thank you for your reply,
No. This situation belongs to just one squash breeding line. Actually, this line was normal 3-4 years ago but then this disorder appeared.
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And what are your recommendations after Apple burr knot is observed
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Possibly all symptoms of Agrobacterium tumefaciens infection including plasmid transfection, but I refer to an old classic paper of E Stover and C Walsh http://hortsci.ashspublications.org/content/33/1/92.full.pdf
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While working on root-knot nematode's hatching rate, there are some isolates' egg-mass that did not hatch in some treatments while others did. We want to know if it is the effect of the treatment or something else. Is there anybody that could help with explaining egg-mass chemical structure and physiology?
Also, any information on the egg's and nematode's cell walls and molting physiology?
Does the availability of O2 affect the egg hatching? What affects the egg-mass?
Thank you so much in advance.
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As far as experienced by myself, Meloidogyne chitwoodi and M. hapla are quite easily hatching in water. From one tomato plant 1 million juveniles can be obtained within 10 days from a spray-mist chamber. Those eggs that do not hatch are embryonic eggs. Furthermore, there is a possibility to stop eggs from hatching by adding a small amount of sugar(?) to the water. Embryonic eggs will develop into mature eggs but will not hatch. This method was developed by a breeding company in The Netherlands (HZPC) to make sure all eggs would hatch at the same time when they were needed. I am not 100% sure it was sugar they added.   
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I'm working on the effects of climate change on endemic plants in the Mediterranean regions and I'm looking for some recent bibliography to read as background.
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If you look into my latest publications you will find several papers in mediterranean endemic halophytes and climate change impacts both by modelling approaches and by mesocosmos trials.
Cheers
Bernardo Duarte
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Generate disease free plants of release variety.
develop methods of rapid testing for main diseases.
Maintain genetic purity from one generation to another.
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Dear Norbert
Yam being a vegetatively propagated crop, much of the seed multiplication procedures used for potato, cassava etc... should work. A major difference with potato, for what I know, is that yam tubers are much larger than those of potato, meaning that they're often cut before planting. This makes the 'usual' certification as developed in potato quite difficult to enforce, because certification applies to entire turbers, not tuber pieces. This is a problem with some (mainly north American) potato cultivars, which have very large tubers and are also cut before planting.
A major issue in any seed program is how you store the seed material once it has gone throuygh inspection or certification. The availability of proper storage facilites, with adequate temperature and ventilation, is of great importance.
For seed production, there are also concerns about cross-contamination risks with the ware crops. This is why seed prodducting regions are often different from the maincrop areas. This in turn raises a logistic proble for seed transportation.
A colleague of mine, working with potatoes in developing countries several years ago, stated that 'seed potatoes requires storage houses, roads and electricity' rather than land and water. of course, they also need the land and water, but this was a way to poiint out that the storage pahse in seed production is just as important, and sometimes even more important, than the field production phase. I guess the same statement would apply just as well to yam seed.
Didier
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More and more opportunistic bacterial pathogens like Serratia, Pantoea, E. coli are isolated from plants and cause new plant diseases. Is there an increasing risk for people?
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Hi Alex, since it seems that you are familiar with literature on serratia as a plant pathogen, is there (in any of these publications) standard protocol which could be used to test serratia strains virulence in plants (like using squash leaves?). I have only used insect models for testing serratia virulence and it would be super neat to be able to test also same kind of ideas in plants
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I'm working with walnut rootstock. I noticed a lot of plants have white streaks/fuzzy white clouds around the callus. They made the plants grow slowly and made the callus turn dark brown/black. Sometimes, no callus form at all. Could you guys suggest some ways to control it? Would PPM or streptomycin help? Thanks for any thoughts.
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I use chloramphenicol to control bacterial contamination but use it during surface decontamination. if incorporated in the culture medium it can slow the growth of cultures
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Can anyone tell me what I could see from the value of N, P, K and Zn, pH to infer the change of available nutrients to plants or uptake of nutrients, etc? Please see the attachment.
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How you applied Trichoderma and which spp.?
You have to give Trichoderma in some times intervals.
After giving Trichoderma besides the controlling the pathogen, you also want to see the NPK from Tricho treat soils?
You may check NPK but how you apply your treatment it is also important.
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The native medical plant “Clammy Inula” (Inula viscosa L.) (family Compositae), is a perennial weed native to the Mediterranean. It grows on hill slopes, damp habitats, and roadsides. In folklore medicine, the plant is used for therapeutic purposes, such as a diuretic, topical anti-inflammatory, haemostatic, and for other purposes. Aqueous extracts of I. viscosa were shown to exhibit antifungal activity in vitro for phytopathogenic.
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Dear Dr. Al-Masri,
I know very well Inula viscosa and odor of its leaves. It is very common near of my house (South-East of France) and in all south of France on calcareous soils. I was ignoring its medicinal use.
But I know well this plant as very useful natural reservoir of one Hymenoptera (Chalcidoidea Eupelmidae) (named Eupelmus urozonus, which is probably a biological complex of species). In Inula, E. urozonus parasitises larvae of one Trypdaetidae (Diptera). Useful plant (in Mediterranean south of France) for biological control of the Olive fly (Bactrocera oleae) and of the Olive moth (Prays oleae).
Sincerely yours.
Dr. André Panis, Scientific Associate at French National Research Institute for Agriculture
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There is a possibility that due to some side effects of fungicide application certain active ingredients and potentially whole classes will be prohibited in future for use in agriculture. What are our options? What new resistant varieties, chemistries, biopesticides or biological control agents will be available for efficient disease control in cultivated plants? Which alternative approaches for plant protection will be pursued and employed to maintain the supply of raw food produce with the high standards of environmental protection?
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Hello Srdan,
Another alternative added to the above list that proposed by Dr Sidhu is the use of Plant Elicitors or activators which increase the plant immune system and induce its resistance against pathogen by eliciting the salicylic acid SA pathway... For more details, please check the attached paper.
Regards,
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Pathogen density in the root and soil.
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I have quantfed by collecting the soil under the canopy and saturating with water in a foam cup with a drainage hole overnight .Dilute the soil in ratio of 10 ml soil and 90 ml 1% water agar. Plate 1 ml of the soil slurry on cma parph and do 5 replicate. Count the phytphthora colnies. Multiply the total times two, that will give you #of propagule/ cm3 of soil.
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I found in some research paper that no till reduces the common root rot infection in wheat. I am curious about the any physiological or environmental region behind it.
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Thank you Alex
water stress in the upper layer of soil due to NT system could be a reason of CRR reduction.
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Bud rot (also called pudricion del cogollo or Amarelecimento fatal) wiped out thousand of hectares of oil palm plantations in South America (Colombia, Ecuador, Brazil, Peru).
I have found few reports about this disease in Asia (Kerala - India) and Africa (Congo).
Does someone know about incidence of Bud Rot in Asia or Africa ?
Im a soil physicist doing a review about but rod incidence in oil Palm plantation and its relation to soil climate in the world. As in this forum participate many Asia and Africa oil palm stakeholders I decide to send this question and thanks in advance any help.
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Use of chemical pesticides in plant/crop protection are becoming regulated and restricted due to their severe adverse impact on environment and human health. However, productivity, profitability and competitiveness of agriculture and forestry must increase at the same time. Pesticides though have been a major factor contributing to the increased crop yields in modern agriculture, but associated problems of environmental degradation that in turn has a marked influence on the economy, health and quality of life have become issue of global concern. Furthermore, resistant strains of pathogens rapidly arise to many new systemic pesticides and generation of new pesticides is becoming more complex and expensive. The difficulty of developing ecofriendly pest control agents has increased their cost and reduced their number that is available. At this crucial juncture, providing alternative means of disease control that are effective and economical and could reduce the dependence on pesticides has become warrantable. Hence, the question emerge – like human beings, is it possible to immunize plants in early stages to induce a stronger self defense capacity against pest and diseases?
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Thanks a lot to all the four respondents. I want know further that "Is there any known formulation comprising growth promoting agents, micronutrients, and protecting substance with broad spectrum efficacy against pest & diseases which can be applied as buster dose in the potting mixture while raising plant in the nursery or in the soil while transplanting the plant in the field". If such a formation exists or could be developed, it would be great help to the poor farmers and plant growers.
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Humans are suffering from many diseases due to eating bunted seeds.
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Bunted grains could be separated by using salt solution.
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For fungal disease.
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The best method is to to prove Koch's postulate (inoculation step in sterilized/autoclaved soil by different methods viz. adding the pathogen culture in soil, adding spore suspension, plant sterilized seed/seedling and observe the symptoms). No other method will be fool proof than this pathogenicity test.