Photinia is about 4 years old, in a semi-sunny semi-protected position, has thrived till about 2 weeks ago when I started to notice that the leaves were not as perky as usual (seem to be half drooping), and around 70% of them have gone quite a deep red colour. There is new growth/flower coming through at the ends of many of the stems (looks like mini purple flower heads). I thought it may be dry, so watered it 10 days ago, but seems to have had no effect. Any ideas please.
It sounds like a root rot, but there are a few that it could be, such as cotton root rot, phytophthora root rot or root rot stemming from poor drainage.
Check the roots and base of the plant for damage. You can try drenching the soil with a fungicide which will work on some forms of root rot. But some of the root rots are fatal once the plant is infected.
Keep a close eye on nearby plants. If they start to fail in the same way, than it is an incurable form of root rot and the plant must be removed ASAP or it will continue to spread.
Prune photinia sometime during early spring through early fall--late spring, early summer being the best time. Unruly plants can be cut back 6 inches to the ground and will come back--annual pruning will help keep them maintained and manageable. They can take a pretty severe pruning, so you can cut them back to a manageable size without harming them.
Info on plant spacing for red tip photinia.
About 3 1/2 to 4 foot spacing should be sufficient. The following article should be of some help to you: https://www.gardeningknowhow.com/ornamental/shrubs/photinia/growing-red-tip-photinia.htm
Will cropping help my red tip photinias to spread out so they will provide a hedge like appearance? If not, what can I do? I believe they were planted approx. 4 ft. apart.
When you cut photinias back, you can expect to see an increase in growth. Pruning often takes place in spring. You can simply prune them for shape as needed, which will result in fuller growth, or perform drastic pruning for unruly shrubs. Red tips are excellent candidates for rejuvenation pruning. To rejuvenate the plant, cut it all the way back to the ground...to about 6 inches. It should grow back nicely and you can expect to see 3 to 4 feet of new growth the very first year.
What pest eats the leaves of the photinia red tip?
There are several it could be, from deer and rodents to slugs to beetles. What kind of damage are you seeing on the leaves? Are they being chewed off entirely, leaves and twigs (deer), or are you seeing small sections of the leaf chewed with chewing damage on the branches (rodents), or are their irregular holes in the inside of the leaves (slugs), or is it on the edges of the leaves (beetles)?
Mostly the edges of the leaves, but whatever it is it is eating most of the leaf, but I can't find anything around them and as cold as it has been I know the grasshoppers aren't out yet. I am in New Mexico and the rest of the plants don't seem to getting any damage to them, only the Photinia.
My son cut all 8 of what became trees. They had not been trimmed for 9 years. Now the stumps have all new growth with that disease and I'm not sure what to do with them or how to keep them trimmed.
Prune photinia sometime during early spring through early fall--late spring, early summer being the best time. Unruly plants can be cut back 6 inches to the ground and will come back--annual pruning will help keep them maintained and manageable. They can take a pretty severe pruning, so you can cut them back to a manageable size without harming them.
As for disease issues, photinia red tip is very susceptible to the fungus leafspot, called Entomosporium, that can defoliate photinia plants. Plant photinia in full sun and provide good air circulation. Remove and destroy fallen leaves,prune off diseased twigs. Avoid overhead irrigation. Fungicide sprays (such as copper-based products or neem oil) are also generally necessary for this disease, beginning from bud break and applied every ten to fourteen days until al lfoliage has matured. Mature foliage is no longer susceptible to infection.
Is red tip photinia plant deer resistant?
They are generally considered deer resistant, but deer will eat anything if they are desperate enough and even nibble on these shrubs on occasion. However, you could try placing other deer-resistant plants around the perimeter of your home or even protect the shrub with a cage. Deer usually steer clear of any plant that is fuzzy or prickly, extremely aromatic, or excessively tall or short.