THE AGRONOMIST ANSWERS ON HOW TO GROW AND CARE FOR PLANTS
The leaves turn yellow, dark spots form and then my photinia dies
QUESTION FROM MARCO
I have a problem with my Photinia.
I have owned this plant for about 10 years, but in the last 3-4 some plants have died and soon others will die: initially the leaves turn yellow, have dark spots and then the plant dies (see photo).
I heard the nurseryman who sold me the plants years ago, he said that the problem is due to water stagnation: which is not true, because I removed the dead plants and there was not a trickle of water (even fertilizing the plants with Nitrophoska Gold and chimney ash I dug a ditch along the whole hedge and about 50cm deep).
I contacted the nurseryman again and he still believes in his opinion .. water stagnation and the only solution is to change the type of plant (the nurseryman is very disinterested in my problem).
The hedge extends for 50 meters, not all of it is battered, the less sunny part is in better shape and hasn't died of plants in the course of its life? But slowly it begins to have problems with leaf yellowing and brown / black cars on the leaves.
Spring fertilization: in addition to Nitrophoska Gold (slow release) and chimney ash, I administered iron sulphate diluted in water. I then discovered that the latter is not much use as the plants cannot assimilate it so I was advised to use the IRON CHELATE administered via FOLIAR (given the severity of my problem) for 3 times a year when there is no direct sunlight on the plant.
Dead plants: I noticed that dead plants lacked small roots: they had a few large roots but no small roots.
In some specimens, near the collar of the plant there was a white patina according to the hypothesis of the fertilizer dealer the problem was due to root rot: caused either by stagnation of water or by fungi and also by iron chlorosis.
So I started to treat the plant with these products:
Before this treatment, I was simply using an insecticide against aphids at intervals of 1 time every 30 days from spring to late September / early October.
Since I started this treatment I have noticed some improvements but I certainly cannot say that the plant is as strong and lush as a few years ago .. certainly at least, for now, no more plants have died .. but I would like to have your opinion on how can I save the plant.
I have a suspect concerning my neighbors and bordering the hedge, (planted 90cm from MY border and another just over 2m): isn't it that they may have given the hedge some herbicide with foliar action? Or throwing out some bleach? I can say that relations are certainly not good.
I await your news
Thank you for your availability
P.s. I am attaching some photos dating back to July and August 2008. In case you would like to have more do not hesitate to contact me. Marco
Dear Mr. Marco,
I try to answer your question about Photinia, hoping to improve the phytosanitary conditions of the plant.
I would rule out the hypothesis of damage from the repeated insecticide treatments you carried out on the hedge. I would say that the yellowing and browning of the leaves are certainly due to the foliar absorption of chemical products of any nature, phytosanitary products, for domestic use such as bleach, various products for household hygiene. The absence of new roots is the direct consequence of the weakening of the plant due to the death of the leaf apparatus. So it was a harmful absorption of toxic substances for the vegetative system of the plant.
As it is very difficult to determine what exactly hit the plants without a chemical analysis, we must rely on their resilience to help them as best we can. Therefore I advise you to water the whole hedge abundantly without exaggerating and a few days later (4-5 days) you must cut all the dry and diseased branches, remove them and burn them.
After about 2 months (in mid-November) he must shorten the healthy plants by doing a nice not very poor pruning, that is, without completely topping the plant. After pruning, repeat a treatment with Bordeaux mixture and without exaggerating with the doses (to be strictly adhered to the recommended doses according to the treatment period) shown on the label and then after 15 days you must always repeat the treatment with Bordeaux mixture.
At the end of February, fertilize with the same product you have already used, Nitrophoska blu, at a dose of 500 gr / plant.
I wish you a good recovery of your Photinia.
Dr. Arianna Esposito