Plants turning yellow outdoors (PICS)

[pahut]

Hey guys,

Am running an outdoor grow here in NZ (thread here https://www.icmag.com/ic/showthread.php?t=367683) but am having issues with leaves turning yellow quite dramatically over the past few days.

Does anyone have any advice or diagnosis on these pics?

They're drinking bore water and getting a feed of Seasol once or twice a week.

 

[YukonKronic]

I think maybe Iron... give a couple a dust of blood meal (tablespoon or three spread evenly on top of soil... careful. Blood is hot.) if they recover you have your answer

If they’re quite brittle as well it might be Sulfur.


From the Joe Fresh guide:


Iron Deficiency

iron-deficient leaves show strong chlorosis at the base of the leaves with some green netting. The most common symptom for iron deficiency starts out as an interveinal chlorosis of the youngest leaves, evolves into an overall chlorosis, and ends as a totally bleached leaf. The bleached areas often develop necrotic spots. Up until the time the leaves become almost completely white they will recover upon application of iron. In the recovery phase the veins are the first to recover as indicated by their bright green color. This distinct venial re-greening observed during iron recovery is probably the most recognizable symptom in all of classical plant nutrition. Because iron has a low mobility, iron deficiency symptoms appear first on the youngest leaves. Iron deficiency is strongly associated with calcareous soils and anaerobic conditions, and it is often induced by an excess of heavy metals.


Iron is an important component of the plants enzyme and is also important for the transportation of electrons while photosynthesis is happening...


Iron reacts with many of the components of nutrient solutions, which will cause a nutrient lockup to occur, If you add to much Iron without adding enough Phosphorus, you can contribute to a phosphorus deficiency , so watch out how much iron and phosphorus your nutrients have. The Leaves on the plant can turn a pale yellow along the growing shoots, while the veins remain dark green. When you have pH imbalance, it can make iron insoluble. The tissue between the veins becomes pale or white, kind of mimics the magnesium deficiency, but not yellow, iron has the white where the yellow would be on the magnesium deficiency. The deficiency starts with the lower and middle leaves, while the new leaves become completely lacking in chlorophyll, but with little or no necrotic spots. The chlorotic mottling on new leaves starts first near the bases of the leaflets, so the middle of the leaf appears to have a yellow mark. Iron is difficult for plants to absorb and moves really slowly in the plant.
Harder for outdoor plants to absorb when in hot weather. Parts affected by the Iron Deficiency are: Young leaves and Petioles.

To much Iron can cause a problem that looks like a PH imbalance, Brown spotting on the top leaves, mainly fan leaves. Can affect the whole plant. Iron Toxicity is rare for Ph below 5.5.



Problems with Iron being locked out by PH troubles
Over watering, pests nematodes, not enough drainage, like not enough perlite. High ph, Soils with low iron, High Phosphorus, Excess Zinc, manganese or copper.



Soil

Iron gets locked out of soil growing at ph levels of 2.0-3.5
Iron is absorbed best in soil at a ph level of 4.0-6.5 (Wouldn’t recommend having a soil ph of over 7.0 in soil) anything out of the ranges listed will contribute to an Iron Deficiency.



Hydro and Soil less Mediums

Iron gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-3.5
Iron is absorbed best in Hydro and Soil less Mediums at ph levels of 4.0- 6.0 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to an iron deficiency.











Sulfur Deficiency


Leaves show a general overall chlorosis while still retaining some green color. The veins and petioles show a very distinct reddish color. The visual symptoms of sulfur deficiency are very similar to the chlorosis found in nitrogen deficiency. However, in sulfur deficiency the yellowing is much more uniform over the entire plant including young leaves. The reddish color often found on the underside of the leaves and the petioles has a more pinkish tone and is much less vivid than that found in nitrogen deficiency. With advanced sulfur deficiency brown lesions and/or necrotic spots often develop along the petiole, and the leaves tend to become more erect and often twisted and brittle.

Sulfur plays an important role in root growth, chlorophyll supply and plant proteins. Just like iron, Sulfur moves slowly in the plant, hotter temps will make Sulfur harder to absorb like iron. But unlike iron, Sulfur is distributed evenly throughout the plant, mainly the big fan leaves. Sulphur is also a very important element in vegetative growth.

First signs of a Sulfur deficiency are pale young leaves. The growth of leaves will remain slow, but the leaves can also get brittle and stay narrower than normal. Can also have small mutated leaves, along with the buds on top of flowering plants will die off. The growth if the plant can be stunted as well as yellowing of the younger leaves and new growth. Unlike a magnesium deficiency where it starts from the leaves tip and around, sulfur starts from the back of the leaves on forward to the middle of the leaves. The Stems become Hard, thin and may be woody. Some of the plants may show orange and red tints rather than yellowing. The stems will increase in length but not in diameter. Leaves will then be stiff and brittle like glass and fall off soon. Parts affected by a Sulfur deficiency are: The whole plant can be affected as well as young leaves, leaf veins.

Too much Sulfur will cause your plants to be small along with the size of your leaves, along with your leaves being brown and dead looking at the tips. An excess of sulfur can also look like salt damage, restricted growth and dark color damage.


Problems with Sulfur being locked out by PH troubles



Soil

Sulfur gets locked out of soil growing at ph levels of 2.0-5.5
Sulfur is absorbed best in soil at a ph level of 6.0- 9.5 (Wouldn’t recommend having a soil ph of over 7.0 in soil) Anything out of the ranges listed will contribute to a Sulfur Deficiency.


Hydro and Soil less Mediums


Sulfur gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-5.5
Sulfur is absorbed best in Hydro and Soil less Mediums at ph levels of 6.0- 9.5 (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to an Sulfur deficiency.

 

[YukonKronic]

Don’t know what bore water is or what’s in seasol but I recommend taking a look at the possibilities regarding lockout from nutrient imbalance. They look healthy aside from what appears to be a very suddenly developing deficiency/lockout... that leads me either to a sudden lack of available iron in the soil or a problem with taking it in.

 

[TanzanianMagic]

- High pH

It is telling that all different sized plants suffer from the same symptoms, which means it is most likely caused by a liquid feed that was given to all of them. High pH will lock out all kinds of micro-nutrients (iron, manganese, zinc, etc.).

- Seasol

Why use that for drought resistance? You should use a light mulch of hemp bedding or chopped straw. And a watering blanket would take care of the rest, especially the smaller plants.