Japanese Black Pine (brown and yellow tips)

[Merfury1989]

Dear members,

I would like to ask how is there is anything wrong about my plants here.
You can see the needles are longer, but I know this is due to lack of sunlight. Currently in my country (Dubai), we are having winters somewhat.

But i also noticed brown tips and yellow tips. Is this okay or there's something wrong?

Few information: I use Peat Moss + Perlite (80/20)
The fertilizer I use is Dyna-Gro Grow at 1/4 teaspoon at every watering (Every other 3 days).

 

[RobertB]

Are they outside? I would move outdoors when you can and see how they do. I’m sure some others on here can give you much better advice.

 

[Merfury1989]

Yup they been outside ever since.

 

[0soyoung]

The yellow tips often mean that the roots were too wet when last year' growth was emerging.. Water a bit less frequently this spring than you did last and/or move them into a larger grained mix. The brown tips could be a further consequence or yet something else in the environment. "Walk" through the pine diagnostic found in the BNut Resources.

 

[Merfury1989]

When you say larger grained mix, are you referring to the pot size or soil type?

I only water when the soil is dry to the touch up to 1 inch.

 

[Shibui]

I find there seems to be a few reasons for yellow needles.
Soil too wet has already been mentioned. Root rot definitely causes this appearance because when the roots die the tree can no longer take up water and dehydration causes needles to go yellow. You should be able to slide the root ball out of the pot and check for healthy, white root tips.
Starvation causes yellow needles. Make sure you are fertilizing frequently. In Dubai you should be feeding through winter as pines won't ever be really dormant.
Too dry causes similar signs as too wet.
Too much shade. Pines are sun lovers and do better with plenty of sun provided you can keep the soil watered.

When you say larger grained mix, are you referring to the pot size or soil type?

I only water when the soil is dry to the touch up to 1 inch.

I'm confident the reference was to soil particle size. Pines are usually planted in soil consisting of larger particles so the soil does not stay waterlogged.

 

[Merfury1989]

TBH the thing which is confusing me is:
- I do water frequently (after they are dry to the touch up to 1 inch), I do fertilise with Dyna-Gro (1/4 teaspoon : 1 Litre) every watering. Plus Pro-tekt (1/4 teaspoon : 1 litre). Plus General Hydroponics PH Down (to bring water PH to 6 to 6.5)
- The plants are outside 24/7
- Its only recently, they developed this trait after 3 months of same routine. I didnt change anything since 3 months on these.
- The soil mix is 80% perlite and 20% peat moss

 

[defra]

To much fertilizer will also cause these symptoms.
I read you fertilize every watering session might be a bit to much.
Normaly i would think its winter so the seedlings will not grow but are dormant so they will not take up the feeding altough i dont know about dubai winters how are the temperatures there in winter?

 

[Merfury1989]

Like highest being 25 degrees (C) during the day.
and lowest being 14 degrees (C) during the night

 

[defra]

Like highest being 25 degrees (C) during the day.
and lowest being 14 degrees (C) during the night

So that is for me basicly summer lol
I would stop fertilizing for a while keep soil moist not wet pine prefer to be little dryer and see if they will get better.
im am not sure how much
Jbp needs winter dormancy

 

[Merfury1989]

Ok let me try, and see how it goes.

 

[Merfury1989]

How do I mimic winters in my climate zone though?

 

[0soyoung]

A refrigerator, but I don't think it is necessary. In think JBP can be 'tropical'. I know of people growing them in Florida, Caribbean Islands, and Brazil. You may not, however, be able to reduce needle length by the usual decandling technique.

 

[Shibui]

JBP definitely grow in warmer climates.
I am told that they can be decandled twice a year to control new shoot length and needle size but that's way in the future. Need to work out what's causing the current problems or there may never be a need to control growth.

80% pertlite is probably good but perlite comes in a range of particle sizes. If you have smaller size that will impact on water holding. 20% peat seems like quite a high proportion, esp for pines. The soil may still be quite wet near the bottom of the pot even when the top inch is getting dry.

Its only recently, they developed this trait after 3 months of same routine. I didnt change anything since 3 months on these.

Many problems are cumulative. The issue does not kill instantly but gradually builds up until we can see symptoms. Sometimes it can be a change in season that causes the sudden onset of symptoms. Root rot can take months to start and more for the trees to show the effects. Nutrient deficiency is also slow to show but I doubt nutrient deficiency is a factor here given your fert regime. More likely nutrient excess as mentioned.

Another possibility has occurred to me based on the dead tips on needles, your hotter location and frequent fertilization. Do you water thoroughly when you do water? Plenty of water running through the soil? Most fertilizers are a mixture of salts. Water flowing through the soil usually leaches excess salts out of the pot.
Most of us understand the term 'salt' to mean sodium chloride but the term is used by chemists to mean a wide range of metallic compounds. Many of the nutrients plants need are found in the form of salts so they are a natural and normal part of all fertilizers.
Excessive evaporation in warm weather and insufficient water flow can leave salts building up in the soil until they reach toxic levels. Saline water supply will make the problem worse. Yellow foliage is one symptom of salinity.
Try flushing the pots with plain water to reduce the possibility of salinity in the soil.

Note that the damaged needles will not recover as the yellow sections are already dead. Improvement will not show up until new needles grow.

 

[Merfury1989]

Hows this soil mix:

25% Akadama
25% Kyuru
25% Pumice
25% Lava rock