Xtremehorticulture

Xtremehorticulture of the Desert

Privet Tree Leaves Black Spots are Disease? No.

Leave a Comment / desert landscaping, leaf disease, leaf drop, leaf spots, Ligustrum japonicum, rock mulch /

Q. I’m sending you a photo of a leaf from my privet tree that has some kind of fungus. Can you suggest some fungicide for me to use? Spotting on privet leaves. It could be a disease problem but it would most likely not be there if the tree was getting proper care. A. I think it is just a lack of good nutrition and perhaps a lack of adequate watering rather than a disease caused by a pathogen like a fungus. Even if it were a fungus disease, it is more susceptible to disease if it is in poor health. However, too much irrigation water applied too often can look similar to this.             Not enough water usually results in leaf drop in the early stages of stress with this tree. I will post your picture on my blog for readers to see your particular problem.             Japanese privet does much better in mixed landscapes rather than alone in rock mulch, if you have it in rock mulch. They do not like soils that develop in a rock environment and have trouble picking up the right nutrients from these types of soils to stay healthy. Please be aware that this tree is not a desert plant so it will require more care to keep it looking good. EDDHA found in the ingredients of an iron chelate fertilizer             Without soil improvement you might try giving it a better fertilizer product. Fertilizers for trees and shrubs from manufacturers such as Miracle Gro, Peters, Jobe’s fertilizer spikes and others will provide better nutrition for the plant than using an inexpensive agricultural fertilizer. Add to this an iron product that contains the EDDHA chelate (look at the ingredients).             Specialty fertilizers like these are not inexpensive. However you can save some money by not using it each time you fertilize. You can make an application and then boost plant performance by using just a little bit of nitrogen fertilizer when the plant needs it.             But if the plant is in rock landscape you will need at least one expensive fertilizer treatment annually to improve your plant performance under the poor soil conditions of rock mulch landscapes.

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No Fear of Disease after Spraying Liquid Fertilizers

1 Comment / bacterial leaf spot, leaf disease, Micronutrient sprays /

Q. Can foliar spraying micronutrients like iron on fruit trees cause bacterial leaf spot to form or spread? I have had problems with bacterial leaf spot on my nectarine trees but last year the leaves weren’t affected as much. I don’t want the pathogen to spread again. A. Where do you live? Who made this diagnosis? I have not heard of bacterial leaf spot forming in the dry desert. In more humid climates it can be more common. The leaf spots on leaves should be surrounded by a yellow halo if it is bacterial leaf spot. Some iron sprays can cause staining on developing fruit and can resemble disease. This is iron staining quince fruit. Use iron chelate sprays if fruit is present. Bacterial infections usually require wet or humid environments and warm to hot temperatures or insects to spread the disease. And these wet/humid environments must be present over a long enough period of time usually many consecutive hours. It would be possible if the plants are crowded together so that the leaves cannot dry or there is an air movement to help dry them. Overhead irrigation such as sprinklers could also contribute to a problem. However, applying foliar micronutrients early in the morning so the leaves have a chance of drying before nightfall there should not be a problem. And spray early in the season. Some diseases like shot hole fungus are prevented with properly timed fungicide applications containing copper. Copper fungicides can also be used to help prevent some bacterial infections like bacterial Leaf spot. The pathogen or bacteria are already present on stems and move to the foliage early in the spring. The leaves just need the right environment (temperature and humidity or degree of wetness) to cause infection. It also helps if the canopy is not dense so there is air movement to help dry the leaves. In your pruning you should create enough space between branches to allow for some sunlight to penetrate inside the canopy and reduce shading. You probably have been told that there are not many pest control products for bacterial diseases but a fairly common fungicide like Bordeaux can give you some good protection if applied when temperatures get warm. Some of the disease potential can be removed through pruning in the winter.

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