Is high nitrogen harmful during leaf fungal disease?

[proninyaroslav]

I usually fertilize trees with high levels of nitrogen (18-18-18 or 19-6-20), but this years some trees have a fungal infection due to the wet and cold spring.
I've heard that high nitrogen during this period make trees more susceptible to fungal infections, is that true? But what then to do with those trees that are at the development stage and require high nitrogen?

 

[Gabler]

I usually fertilize trees with high levels of nitrogen (18-18-18 or 19-6-20), but this years some trees have a fungal infection due to the wet and cold spring.
I've heard that high nitrogen during this period make trees more susceptible to fungal infections, is that true? But what then to do with those trees that are at the development stage and require high nitrogen?

I've never heard that. Excessive watering is usually a catalyst for fungus.

 

[River's Edge]

I usually fertilize trees with high levels of nitrogen (18-18-18 or 19-6-20), but this years some trees have a fungal infection due to the wet and cold spring.
I've heard that high nitrogen during this period make trees more susceptible to fungal infections, is that true? But what then to do with those trees that are at the development stage and require high nitrogen?

I would focus on managing the soil moisture during wet/ cold conditions. Provide some cover or protection from heavy rains. Reduce the watering to ensure proper levels of moisture in the pots.
On another note you can get excellent development of Bonsai with lower levels of Nitrogen in your fertilizers. Consider switching to a fertilizer that has all three main elements below ten. Make sure that the trace elements are present in the type you choose! High quality Bonsai are usually developed with controlled growth rather than excessive growth. This allows one to develop more appropriate internodes length and more appropriate foliage. Much easier to compact and condense foliage and pads for design if growth is managed rather than pushed. Might seem like a slower approach but requires less corrective action and restructuring in the long run.

 

[proninyaroslav]

I've never heard that. Excessive watering is usually a catalyst for fungus.

Do you mean wet leaves or watering in general?

On another note you can get excellent development of Bonsai with lower levels of Nitrogen in your fertilizer

Most of my trees require the developing of primary and secondary branches, or even a trunk. With a high nitrogen content this can be achieved faster.

 

[River's Edge]

With a high nitrogen content this can be achieved faster.

My point was faster does not always mean a better result. You often get large internodes with the problem of difficulty compacting branching and foliage for refinement with excessive nitrogen. Lots of research to back that up! Optimum amounts are less than 18 as you suggested you were using.

 

[August44]

I would focus on managing the soil moisture during wet/ cold conditions. Provide some cover or protection from heavy rains. Reduce the watering to ensure proper levels of moisture in the pots.
On another note you can get excellent development of Bonsai with lower levels of Nitrogen in your fertilizers. Consider switching to a fertilizer that has all three main elements below ten. Make sure that the trace elements are present in the type you choose! High quality Bonsai are usually developed with controlled growth rather than excessive growth. This allows one to develop more appropriate internodes length and more appropriate foliage. Much easier to compact and condense foliage and pads for design if growth is managed rather than pushed. Might seem like a slower approach but requires less corrective action and restructuring in the long run.

What fertilizer do you use pls that is as you mention with elements below 10 and has trace elements too? Thanks

 

[RoadManDenDron]

Just seen this post, hope this information is useful even at a later date

Nitrogen growth causes cells to elongate, N is also a luxury element, the trees will assimilate N even when it doesn't need it.

Assimilating N uses up to 70% of the energy created from photosynthesis.

Long stretched cells = thin cell walls = more susceptible to insect or fungus attack

Smaller cells = thicker cell walls = less susceptible to insect and fungus attack

I try to encourage plants to grow vigorous and healthy with high BRIX, mostly on their own steam, my strongest fertiliser is 5 N, even for developing material

But I do use biostimulants, amino acids, calcium and CO2 supplementation from seedling stages to encourage more photosynthesis, more energy and more growth rather than less growth but stretching the cells that are there

 

[R0b]

Just seen this post, hope this information is useful even at a later date

Nitrogen growth causes cells to elongate, N is also a luxury element, the trees will assimilate N even when it doesn't need it.

Assimilating N uses up to 70% of the energy created from photosynthesis.

Long stretched cells = thin cell walls = more susceptible to insect or fungus attack

Smaller cells = thicker cell walls = less susceptible to insect and fungus attack

I try to encourage plants to grow vigorous and healthy with high BRIX, mostly on their own steam, my strongest fertiliser is 5 N, even for developing material

But I do use biostimulants, amino acids, calcium and CO2 supplementation from seedling stages to encourage more photosynthesis, more energy and more growth rather than less growth but stretching the cells that are there

That is what they thought me.