High N and diseases

[keithrs]

I was curious if high N fertilizers play a role in feeding diseases and fungi on plants? Or maybe the type of N used?

[camille1585]

High nitrogen ratio feed results in soft, lush and leggy growth that it much more susceptible to disease, and also more welcoming to herbivorous insects. The cause of this is that plant cell walls are thinner, making it much easier for fungi and other pathogens to break through. Insects are attracted because they are usually nitrogen limited, and these plants make an ideal (and rich) food source. Another effect of too high a ratio of N is that blooming is often times inhibited. So all in all it's best to stick with a balanced NPK fertilizer.

[OrchidThief79]

I think the main culprit in fungal growth is excess moisture. Fungi need a moist environment to grow. Example: you can fertilize a patch of mushrooms as much as you want, but if they don't have a moist environment they won't grow. You don't have to fertilize your bathroom tiles to get mildew to grow.

[Bud]

Wow...thanks Camille; thats good to know!

[stefpix]

can you get rid of fungi for good with sun exposure?

[camille1585]

Originally Posted by OrchidThief79

I think the main culprit in fungal growth is excess moisture. Fungi need a moist environment to grow. Example: you can fertilize a patch of mushrooms as much as you want, but if they don't have a moist environment they won't grow. You don't have to fertilize your bathroom tiles to get mildew to grow.

Very true, but having soft growth makes it even easier for the fungi to get in. Cell walls are the first line of physical defenses has against a microbial attacker. Soft cell walls makes it so much more susceptible to the cell wall hydrolyzing enzymes produced by pathogens to gain entry. So in ideal conditions for fungal growth, an N overfed plant is much more likely to get infected.

[keithrs]

Originally Posted by OrchidThief79

I think the main culprit in fungal growth is excess moisture. Fungi need a moist environment to grow. Example: you can fertilize a patch of mushrooms as much as you want, but if they don't have a moist environment they won't grow. You don't have to fertilize your bathroom tiles to get mildew to grow.

I agree with you on the moisture, but if the fungi doesn't have something to feed on(like paper on your drywall) it won't grow.

I guess what I'm trying to ask is will fungi grow/spread faster using a high N fertilizer at full strength vs it diluted down to 1/4 strength?

As far as sun gos, I would guess that it would depend on the strain of fungi..... I have mushroom that grow in my lawn in full sun.

[OrchidThief79]

I could be wrong, but I think fungi get the bulk of their nutrients from the decaying organic matter they are growing on. They are necrotizing organisms. They aren't plants and they don't have the roots and vascular tissue of plants, so I doubt that fertilizer will accelerate fungal growth.

[camille1585]

Originally Posted by OrchidThief79

I could be wrong, but I think fungi get the bulk of their nutrients from the decaying organic matter they are growing on. They are necrotizing organisms.

Somewhat wrong. There are 3 types of fungi: biotrophs, hemibiotrophs and necrotrophs.
Biotrophic fungi colonize living tissue get their nutrients from living host plant cells. They live as long as the plant lives.
Necrotrophic fungi will kill their hosts in order to feed on the decaying plant material
Hemibiotrophs need living plant tissue during the colonization process (so are biotrophs), but as the reproductive part of their cycle needs to be on dead tissue they then kill their host, and so they become necrotrophs.

Originally Posted by OrchidThief79

They aren't plants and they don't have the roots and vascular tissue of plants, so I doubt that fertilizer will accelerate fungal growth.

Yes, excess fertilizer will accelerate fungal growth. True they are not plants, but they are living organisms and depend on the same nutrients for their building blocks. Another research group at the university I work at has done work on this. They did a meta-analysis and found that excess nitrogen stimulated and enhanced the development of a wide range of pathogens. When there is a lot of nitrogen available the pathogens can easily adjust their metabolisms to acquire more of it from the plant, and they then grow+spread much faster. How well a certain pathogen will take advantage of the excess food depends on their infection strategies and genetics.

They also found that lack of nitrogen can have a similar effect, because this weakens the plant, making it easier for the fungi to breach plant defenses and easier to colonize cells.

[OrchidThief79]

Originally Posted by camille1585

Yes, excess fertilizer will accelerate fungal growth. True they are not plants, but they are living organisms and depend on the same nutrients for their building blocks. Another research group at the university I work at has done work on this. They did a meta-analysis and found that excess nitrogen stimulated and enhanced the development of a wide range of pathogens. When there is a lot of nitrogen available the pathogens can easily adjust their metabolisms to acquire more of it from the plant, and they then grow+spread much faster.

LOL Considering this is exactly what the original question was, why not mention this in your earlier post? Well there's your answer.