Biological Control Of Plant Diseases - Science topic

Biological control is effective when the population is low and there is no pesticide application as these agents are more sensitive to these chemicals. An earlier endogram was thereafter that no resistant population was discovered. So biocontrol can be part of IPM not as whole.

Insecticides Acephate & Fenitrothion could be applied to controlling tea insects.

Please take a look at these useful RG links.

I am boring on the topic of disease rating, because the longer you study disease, the more important the topic becomes to you. In one disease I study (boxwood blight), I could spend a lot of time determining % leaf area with lesions. However, the diseased leaves tend to drop off no matter what the size of the lesion, so I simply count the number of diseased leaves out of total leaves. In another disease I study (powdery mildew of squash), the total lesion area is correlated with the altered metabolism of the plant and subsequent yield, so % leaf lesion is appropriate. In your situation, you need to ask yourself how much transpiration is affected in partially wilted plants, and whether those plants will eventually become fully wilted.

Just citing myself: "Soil-borne microorganisms such as Agrobacterium spp. are well adapted to aquatic environments, and their growth in mineral substrates is favored by the absence of normal soil microbiome (Ignatov et al. 2016). We compared rock wool mat and coco fiber mat microbiome under cultivated cucumber plants at the stage of fruit bearing by NGS analysis of 16S rRNA gene fragments. 16S rRNA gene fragments were PCR-amplified from total DNA using 3 multiplex pairs of consensus primers. Four amplicon’s libraries were obtained and analyzed on the Roche/454 Life Sciences GS JuniorGS sequencer. Analysis of 16S rDNA profiles placed the bacteria into 9 groups: Flavobacteriales (17.4% in average), Rhizobiales (16.7%), Pseudomonadales (12.9%), Sphingobacteriales (12.9%), Burkholderiales (8.7%), Alteromonadales (8.1%), Xanthomonadales (6.8%), Enterobacteriales (0.18%), and an unclassified bacterial clade (16.3%). The percentages of Rhizobiales clones (including Agrobacterium spp.) were greater in the rhizosphere of plants grown on rock wool mats (infected - 25.9% and control -26.1%) than on coco fiber mats (6.6 and 8.1%). ... Agrobacterium spp. was a predominant part of Rhizobiales clones in infected rock wool mats (72.7%), while infected coco fiber mats had only 32% of Agrgrobacterium spp. in total number of Rhizobiales clones. Root mat disease significantly increased population of Flavobacteriales – 21.9% against 12.8% in control, and population of pectolytic Enterobacteriales (0.36% against 0%). Root mat disease significantly decreased population of Xanthomonadales – 2.25% against 11.4% in control. These results suggest that hydroponic mat bacterial community may play an important role in the changes of cucumber rhizosphere biological conditions during the infection caused by Agrobacterium spp. bv1. The pathogen has extremely high rate of spreading, survival in infected soil, water and substrate, and easy establish new local populations in infected glasshouses. Within 4 months after their first observed symptoms on some 0.5% of plants, the pathogen was recovered from 95% of plant, soil, and substrate samples collected across the glasshouse with 12000 plants (Khodykina et al., 2014b). "

Ignatov AN, Khodykina MV, Kromina KA, Dzhalilov FS. Dynamics of microorganisms in hydroponic system of cucumber in response to Agrobacterium bv1 (root mat) infection. SUITMA 9. ( 9th international congress Soils of Urban Industrial Traffic Mining and Military Areas)

@ Wong, CFU /g soil = Count per Plate/ dilution factor

For example, if 30 colonies are present on 10 ^-6 dilution plate, the calculation will be:

CFU = 30/ 10 ^-6 = 3x 10 ⁷ colonies per gram soil.

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 ...

https://www.youtube.com/watch?v=t04vGdZVxu4

Prof. Paul, you have given good suggestions, but problem is that these vegetable oils does not show consistent results.

Dr. Jawad;

i think we should before diagnoses the agriculture stile before starting any therapy or control programs. my point of view is to try to create a rhizoplan or rhizospher under control with any tested biological control, this procedure i do with soilless culture by using agr-waist substrate and it gave good effects. 

Dear Mehdi Bazoo

Pls. find the attached files

Hoping this will be helpful

Regards

Prof. Houda Kawas

Dear Prof. Mohammed Fayyadh.

You can see the following articles.

Best Greetings

Hi Aishatu

You can follow this scale from 0-7 to measure the disease severity :

0 ¼ no discoloration or mycelial growth on the crown,

1 ¼ discoloration or mycelial growth limited on surface of the cut crown,

2 ¼ discoloration or mycelial growth less than 10% of the crown area,

3 ¼ 11–40% discoloration or mycelial growth on crown area,

4 ¼ 41–70% discoloration or mycelial growth on crown area,

5 ¼ 71–100% discoloration or mycelial growth on crown area,

6 ¼ discoloration or mycelial growth advanced to finger stalks,

7 ¼ finger-stalk rot occurs, causing the fingers to drop-off when handled.

Reference :

Dionisio G. Alvindiaa,

An integrated approach with hot water treatment and salt in the control of crown rot disease and preservation of quality in banana.

 International Journal of Pest Management, 2013

Preservation of the pathogenic spore suspension at -80°C in glycerol is the best way as suggested by Dr. Latif. 

Dear Saniya Sarfraz,

The attached chapter lists the bacterial and fungal strains on the surface of black gram (Vigna Mungo).

Hoping this will be helpful,

Rafik

I'm not a pathologist but my reading says that the whole pile needs to reach at least 60 degrees C at some stage

Dear Jactone:

For entomopathogenic fungi such as Beauveria bassiana and Metarhizium anisopliae water is the carrier vehicle for spores, this must be clean with pH close to 7.0, different values may alter the spore germination.

Best wishes,

Luis Miguel

Hi Geoffrey,

There are a lot of growth medium which requires the use of of yeast extract as a nitrogen source.

Except you are trying to perform any specific assay, there is no reason to add yeast cells to the liquid culture of Metarhizium or Trichoderma. In fact, as you know, they a major contaminant to industrial cultivation of fungi since you can not use antibiotics. Besides, if you are trying to produce fungi conidia think about using semi-solid fermentation with rice or corn as growth media.

Dear Juliano:

The leafhopper Dalbulus maidis can be surveyed in the field using yellow sticky traps. For inoculation of plants of maize for spiroplasma  and maiz rayado fino  monitoring, confined plants of maize can be exposed to 10 AY-WB-infected D. maidis at a uniform growth stage for 7 days. An equal number of plants can have the same treatment with healthy insects. Insects are then removed and plants can be observed for symptom development at 18 days after the first day of insect exposure. All plants can be kept separately in individual plastic plant tube cages. To monitor insect survival on AY-WBinfected and healthy plants, 10 adult leafhoppers of approximately the same age can be added to the individual tube cages. Monitoring of survival can be carried out over 10 days. For the feeding assays on maize, 5 insects of D. maidis can be confined to single leaves using leaf cages. Insects can be observed for 5 days. Leaves can be harvested for trypan blue, DAB and aniline blue staining. Damage can be quantified by counting visible damaged cell areas per unit area of leaf surface.

 Yes ,siderophores  such as pyocyanin and  the antibiotic phenazine produced by a strain of bacterial biocontrol agent Pseudomonas fluorescens can be used against the  pathogen Colletotrichum gloeosporioides in the field . It should be used as prophylacticrather than curative during the initial stages of infection.

you can do by % inhibition of plants or by dual culture assay on plate.

You can also try adding Neem cake or Neem leaf extracts (prepared traditionally) in soil and see if it helps the plant to fight the disease.

For long term storage (-80oC freezer or liquid nitrogen), uredospores can be stored in gelatin capsules, glass vials, plastic bags and aluminum foil pouches.

Argemone maxicana and Eupatorium odoratum can control the rust of cicer, can refer this research paper.

pre-emergence growth occurring in the dark

pre emergence stage : is an heterotrophic growth of seedling in the dark befor the seedling shoot leads the seedlings outside of the soil.

post emergence; is an autotrophic growth after the emergence of seedling apex from the soil

Dear Elaheh,

probably my comment is taken for granted, but to add a point to the useful comments above, do not forget -whenever possible and available - to use resistant tomato cultivars/hybrids.

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.   

spry with fungicide Di-thane M - 45 @ 2.5 g/L of water  at first appearance of disease symptoms, it can be repeated after 10 to 15 days interval if the disease still persist.     

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

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.

Dear Yogesh,

Until the population density of an invasive species is low eradication can be effective. E.g. the successful eradication of Metcalfa pruinosa by pesticides in UK and the Czech Republic. However, strict quarantine is the best solution that is thorough investigation of all kinds of goods and products in order to hamper the introduction of dangerous species.

Hi all

You can also have a look at the following database

All the best

Didier

@Emilio, Hi!

I'm not sure I agree with your minimal infective dose. We regularly detect more bacteria and we don't always have disease. I agree that when all is right: bacteria present, weather conducive and susceptible cultivars, then things move fast!

As you know, in America we "live" with fire blight (FB). Eradication is not an option. The key is management: Copper in early Spring, antibiotics (or blossom protect) when conditions are favorable during bloom, removal of flowers in new blocks, Apogee before petal fall in some blocks and pruning out symptoms as soon as they appear. When efforts are concentrated in the most susceptible blocks = <10 years and susceptible cultivars, FB can be successfully managed.

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,

Dear Fatemah,

As it is not my area of specialization; I can't help you by my experience or knowledge. But I want to help you so here is some idea which I got from internet.

I will send you some research paper soon. Inshallah.

A psychological disorder, also known as a mental disorder, is a pattern of behavioral or psychological symptoms that impact multiple life areas and/or create distress for the person experiencing these symptoms.

How are Psychological Disorders Diagnosed?

The classification and diagnosis is an important concern for both mental health providers and mental health clients. While there is no single, definitive definition of mental disorders, a number of different classification and diagnostic criteria have emerged. Clinicians utilize the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV TR), published by the American Psychiatric Association, to determine whether a set of symptoms or behaviors meets the criteria for diagnosis as a psychological disorder. The International Classification of Diseases (ICD-16), published by the World Health Organization, is also frequently used.

with regards

Qaim Mehdi

Removal of all dry twigs and uprooting of wilted plant is effective

Apply balanced nutrition especially nitrogen through organic sources.

and Growing resistant varieties like Allahabad Safeda, Banarasi supreme etc.

The infection can be minimized by soil drenching with Brasicol and spraying of Bavistin (0.1%) around the roots and leaves at an interval of 15 days.

Please contact Head, Division of Crop Protection , Coconut Research Board, (former Institute) Sri Lanka for details for disease control by BC in coconuts.

In Sri Lanka BCAs are used to control Mosquito which spread the 'Dengi' fever. More information could be get from Medical Research Institute, Sri Lanka. that is a virus imported from Cuba.

Larvae of Black beetle which harm crown of coconut could be control by a virus which is not harmful to human.

Promicothica Kumagi, a beetle which harm coconut leaves at epidemic level had been controlled by a BCA imported from Java in 1970s. Now that BCA is in the natural environment and no longer that beetle is threat to coconut Industry.

I think You have better to check for the limiting temperatures of the bacterium, if it likes lower temperatures and needs low temperatures, You can keep host-pathogen window close using late-heading cultivars that head when it is warmer. However, the best control approach would be the use of resistant cultivars that can be performed in combination with crop rotation and the use of certified healthy/ sterilized seeds in order to decrease selection pressure on pathogen population through restriction of its population and increase of the durability of plant resistance.

best method is digest the fungal cell wall using chitinase enzyme by keeping the mycelium in enzyme over night and centrifuge and isolate the protoplast. Use PEG fuse or try SV40 virus.

If you want to find rare strains present in one environment but absent in another, you should better use a large number of selective media and many samples for both variants (I suggest above 100). Other ways are mostly linked to molecular study without bacteria isolation.

Please, be careful with Nicotiana: HR depends on injected leaf age.

Trichoderma specifically T. harzianum works well against Ganoderma sp.

Ultimately, society expects plant pathologists to control pathogens like bacterial canker. The contract is: "we give you funds; you solve the problem".

So I suggest that the studies you undertake need to lead to control of bacterial canker in tomato.

Ideas:

1. Epidemiology - under what conditions does bacterial canker occur ?

2. Breeding - there are resistant varities in South Africa. Access these and backcross the gene for resistance into locally adapted varieties. Or develop a molecular marker for the gene, so breeders can make the backcross more consistently. Or develop a better inoculation technique that miics nature more closely, with a lower dose than is used normally.

3. Biocontrol - isolate bacteriophages to control the bacterium. And develop a production process and conduct field trials on the use of bacteriophages to control the problem..

Dear D. Calvo,

Aphid movement, stay, foraging, reproduction, interactions are orchestrated by a complicated net of mechanisms which are influenced by many conditions where also the wind direction and intensity may have a role. It is difficult to assess the correlation among the three stimuli you have selected.

there is one research group at CSK HPKV Palampur who have worked on C. truncatum from pea as well as green gram. I will also search for C. pisi from kashmir

Thanks Mr. Tony

Thanks for your reply Touseef. I have already followed the suggestions you gave me. I did a gPCR to check the right annealing temperature and my primers for qPCR give a product less than 150 bp.

I routinely use the Bioanalyzer 2100 CE machine. It can completely replace SDS-PAGE or native-PAGE analyses with far less time and effort. There is an internal standard which helps with data analyses and the software is very used friendly. This CE machine won't be left to collect dust if you regularly do PAGE gels as it will act as a replacement.

It would probably be useful to know, also the date the plant was collected. One should also note if the plant was damaged. Some compounds are produced as a result of stress, such as being attacked by insects. If insects attack plants only during a certain part of the year, the plant probably won't expend energy producing insecticidal compounds during the rest of the year. In addition, plants may be more vunerable to certain insect pests at different portions of their growth cycle and the plant mave have evolved to produce protective compounds only during the vunerable portion of their life.

I quite often use the Wizard Genomic DNA Purification kit (Promega) which does well both for gram negative and gram positive bacteria.The yield and purity obtained with this system is so far good for me, and you can use the purified DNA for many applications including amplifications, restriction digestion, and membrane hybridizations. Visit their we site : www.promega.com

Unfortunately, Amhishek Pyasi's proposed method is used far too often. It is similar to the so-called 'autocthonous' inoculum published in some of the work from Granada, Spain. This is no way to produce inoculum, unless you also want to include mites, nematodes, pathogenic fungi, oomycetes, chytrids, and any other kind of soil inhabitants. Not only that, but such work is scientifically unrepeatable. If you do the same thing the next time, there is no way of knowing if your 'inoculum' is the same as the previous time.

So, what you need to do is to isolate your fungi. If you feel the need to mix species, then you should isolate several species, and mix them yourself at the time of inoculation. That;s the scientist’s job – not to allow random acts of nature to operate. This way, what you do can be controlled and replicated, as should all scientific experiments.

So, you can begin with soil traps of the sort recommended by Abhishek, but not for use as inoculum. The traps will allow you to multiply up some (though unfortunately not all) of the AMF in your soil. Then you extract spores from these pots and use them to establish single species cultures, or better still, isolates (the term isolate should NEVER be used for anything other than a culture established from a single propagule). You can then bulk up these cultures or isolates, but you must ensure you use disinfested substrate and mycorrhiza-free host plants. Once bulked, you can use them as inoculum, preferably after establishing their colonisation potential with trials (most probably number).

As you live in India, I suggest you contact Prof. Alok Adholeya, in Delhi (aloka@teri.res.in), who runs the Biotechnology and Management of Bioresources Division, The Energy and Resources Institute in New Delhi. His group can supply outstandingly good AMF inoculum: obtaining it in this way will save you much work and time.

I am sure that the plant is not infested with fungal/ bacterial/ viral pathogen. The plant definitely suffers from mineral deficiency. The symptom is interveinal chlorosis. Please check for Mg/Mn deficiency or Fe . It will be a wasteful exercise to examine the plant for secondary metabolites

Fadel, I'd like to extract from Theobroma cacao plants and my idea is to verify if applying extracts from resistant plant varietes it could enhancing resistance in susceptible ones. Once is suposed that elicitors would be present in those extracts, am I wrong? Don't worry about english Igor, mine is terrible so!!