Paph sangii

[Elite Orchids]

Hi,

I wondered if anyone has seen these brown markings before on the leaves and can explain what is going on?

It is Paph sangii, it is growing along side similar species that can be tricky and they are all quite happy.

i have had it for 5 years and it slowly grows, it has a couple of roots, but nothing major.

Is it bacterial, fungal or simply too much feed? it gets 500ms most weeks - Peters excel cal/mag 50% with Calcium nitrate 50%

thanks

mark

 

[Ray]

When was it last repotted?

I find that my paphs tend to do that when the salt level it too high, whether that be from overfeeding or accumulation or due to excessive drying.

 

[Elite Orchids]

When was it last repotted?

I find that my paphs tend to do that when the salt level it too high, whether that be from overfeeding or accumulation or due to excessive drying.

Repotted on the 1/12/18 - Bark and Pumice. do you think the brown tips of leaves indicates salt leaves too high??

 

[Paphman910]

Do you know the pH of the water?

 

[tomkalina]

Check Total Dissolved Solids in your irrigation water after you add fertilizer. Your feed rate seems high.

 

[Ozpaph]

are you sure its not spider mites? wipe the under leave surface with a damp, white cloth/tissue and check

 

[Ray]

If your EC units are truly milliSiemens, and not microSiemens, you’re WAY over feeding!

The EC of the Peter’s Excel 15-5-15-5Ca-3Mg is 1.56 mS/cm at 200 ppm N, and at that concentration, the true TDS contribution of the fertilizer would be about 500 ppm. If your units are correct, you’re 1000x that.

If they are really microSiemens, you’ll be in better shape, but without knowing the EC-vs-concentration relationship of the components… (I did some digging for you)

The cal mag is about 7.8 microS/ppm N and the calcium nitrate is about 7.4, so a reasonable estimate for a 50/50 mix is 7.6 microSiemens (0.0076 mS) per ppm N, and for weekly feeding 75-100 ppm N is a reasonable level in my book. If we’re talking microSiemens, you’re at about 75 ppm N, which is fine.

 

[Elite Orchids]

Do you know the pH of the water?

Ph is around 6.2 after the salts have been dissolved and the water corrected.

 

[Elite Orchids]

Check Total Dissolved Solids in your irrigation water after you add fertilizer. Your feed rate seems high.

microSiemens - my bad - i always forget to use the right capital! apologies

 

[Elite Orchids]

If your EC units are truly milliSiemens, and not microSiemens, you’re WAY over feeding!

The EC of the Peter’s Excel 15-5-15-5Ca-3Mg is 1.56 mS/cm at 200 ppm N, and at that concentration, the true TDS contribution of the fertilizer would be about 500 ppm. If your units are correct, you’re 1000x that.

If they are really microSiemens, you’ll be in better shape, but without knowing the EC-vs-concentration relationship of the components… (I did some digging for you)

The cal mag is about 7.8 microS/ppm N and the calcium nitrate is about 7.4, so a reasonable estimate for a 50/50 mix is 7.6 microSiemens (0.0076 mS) per ppm N, and for weekly feeding 75-100 ppm N is a reasonable level in my book. If we’re talking microSiemens, you’re at about 75 ppm N, which is fine.

It is microSiemens - sorry for causing alarm. what do you think the best course of action for me is??

 

[Ray]

I just looked at your repotting reply - personally, I think you're at least 18 months past due to repot.

What is the water quality like? If it has a high alkalinity, that could be the issue (and adjusting the pH does not fix that), or it might simply be the plant wants more water.

 

[southernbelle]

Repotted on the 1/12/18 - Bark and Pumice. do you think the brown tips of leaves indicates salt leaves too high??

I’ve heard professionals say to repot Paphs every two years. You are at 3.5.

 

[Ray]

Steve Male (Fishing Creek Orchids) is one of the best growers I know. He repots everything annually, before his bark even thinks about decomposing, so his "old" and "new" pot conditions are quite similar, resulting in no repotting setback whatsoever.

 

[Elite Orchids]

I just looked at your repotting reply - personally, I think you're at least 18 months past due to repot.

What is the water quality like? If it has a high alkalinity, that could be the issue (and adjusting the pH does not fix that), or it might simply be the plant wants more water.

Noted - i have repotted - we use rain water and the ph today is around 5.6 - though it varies above and below that month by month basis. think it is wise to cut the leaves back?? past the brown parts

 

[Ray]

If you're using rain water, the issue isn't alkalinity!

Repot and flood the plant frequently, never letting it completely dry out.

I wouldn't bother trimming, but you can if it makes you feel better.

 

[Paphman910]

Ph is around 6.2 after the salts have been dissolved and the water corrected.

Your pH is fine. But I am wondering if you had a period of very high summer temperature and the medium dries out so much that it concentrate the fertilizer in the bark media and pumice. This would cause fertilizer burn on the new leaf tip and it happened on my stonei and delenatii as I did not repot in over 3 years. It is worst if grown in coconut husk, perlite and moss as it absorbs so much salt easily.

I usually water a dry mix first with pure water and then I water with fertilizer water. Then I water it again with pure water in 3 day.