Phosphorous is known to play an important role in root growth .Since clubroot is a soil borne disease , there is likelihood that phosphorous treatment will reduce the incidence of clubroot...

@ Jan, an increase in P has little effect while a decrease in P usually decrease the severity of clubroot. In general, less clubroot in alkaline soil than acidic soil. High K concentration increased the severity of clubroot. Absence of S also increased the percentage of clubroot plants. For more details, please have a look of the attached file.

It is caused by the soil-borne fungus Plasmodiophora brassicae which infects susceptible plants through root hairs. Diseased roots become swollen, misshapen and deformed (clubbed) often cracking and rotting. As a result, plants have difficulty absorbing water and nutrients properly.

Treatment

1. Fungicides will NOT treat this soil-dwelling micro-organism.

2. Choose resistant cultivars when possible.

3. Try to prevent the occurrence of this disease by keeping a clean garden and rotating crops.

4. Keep in mind that the disease spores can persist in the soil for up to 20 years. If club root is present you may want to solarize the soil.

5. Control susceptible weeds — mustard, radish, shepherd’s purse — that may be infected to reduce potential buildup of the disease.

6. Carefully remove infected plants and sterilize garden tools (one part bleach to 4 parts water) after use.

7. Raise your soil’s pH to a more alkaline 7.2 by mixing oyster shell or dolomite lime into your garden in the fall. Simple and affordable soil test kits are available to check pH often.

In the current study, a label-free shotgun proteomic approach was used to profile and compare the proteomes of Brassica rapa carrying and not carrying the CR gene Rcr1 in response to P. brassicae infection. A total of 527 differentially accumulated proteins (DAPs) were identified between the resistant (with Rcr1) and susceptible (without Rcr1) samples, and functional annotation of these DAPs indicates that the perception of P. brassicae and activation of defense responses are triggered via an unique signaling pathway distinct from common modes of recognition receptors reported with many other plant–pathogen interactions.

The fertilizer is DAP

what is the Soilś type ?

(NH4)2HPO4 is your fertilizer

what is the type of soil, and the soil

PH ?

Surely suits well to alkaline soils than acidic ones. In general, DAP will raise the pH in the vicinity of the dissolving fertilizer granule for short period of time before the pH goes down. However, DAP should not be placed with the seed at planting but major changes in soil pH will not generally occur unless very heavy applications of DAP are used or DAP is used over a long period of time. Nitrogenous fertilizers will probably have a greater effect on short term soil pH changes because of the H+ ions generated when ammonaical N sources are used and it is converted to nitrate. Most often N fertilizers are used an much higher rates than P fertilizers so their acidification potential is much greater.

Thank you very much. A lot has been mentioned already but i will add a few of my opinion. DAP fertilizer provides both P and N for plants. Adequate nutrients like from DAP will only reduce the severity of the disease if nutrients were limiting in your soil because plants respond to fertilizers well in nutrient deficient soils. If your plants will be grown in a P or N deficient soil, then i guess it will decrease severity of the disease. a nutrient deficient plant is likely to develop disease symptoms than a well nourished plant. you could consider checking different rates of the DAP to see also which quantity can suppress symptoms because only one application rate may not give you best result you can conclude with. I mean you may put little amount and see no differences with control simply because you missed on the DAP amount that respond to club root. Cheers

when DAP dissolved the pH

is 8.2 but when MAP dissolved PH of solution is near to4.2 to 4.5 than

MAP is better than DAP alkaline soils

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