Citrus root rot can become a serious issue for gardeners if left unattended…
A fungal disease that goes by many names: foot rot, root rot, brown rot, gummosis, Phytophthora is an uncommon but troublesome garden occurrence. Essentially, this disease affects the roots of a plant.
While it mainly affects fruit and citrus trees, there are many different species that can be damaged or destroyed, including vegetable crops and nut trees.
Let’s take a deeper look into what root rot or gummosis actually is, the symptoms in citrus trees and the best management if you find your plants infected.
What is Phytophthora root rot?
Phytophthora root rot is a water mould that develops in high moisture and temperature environments. When in favourable conditions, the motile zoospores will produce in large quantities and travel through water systems of rain run off, irrigation or natural waterways.
Phytophthora can actually manifest in two different ways in a plant, through the root or straight from the branches and trunks. If zoospores have moved through wet, moist soil around your plants, they encyst, germinate and enter the root tip. This results in the entire root or rootlet dying, hence the name ‘root rot’.
It can also occur when the Phytophthora zoospores are present in water that is splashed on open wounds or bark crack and creates sap-like ‘gummy’ bulges.
Both versions of Phytophthora can severely affect the growth and health of your tree.
How does Phytophthora affect citrus trees?
According to the University of California Agriculture and Natural Resources, Phytophthora affects the whole tree or plant, and depending on severity, may actually completely destroy it. Here are the signs to watch out for:
Leaf – yellowing foliage and small shoots dying. If citrus weevils are also present on your tree, your leaves may also have notching from adults feeding on them.
Fruit – may be smaller in size and yield.
Trunk and branches – dark water soaked areas will highlight where the infection is active. Lesions will occur on the bark of the tree, as well as at the bud union. Lesions will exude sap or lots of gum, with a brown necrotic patch underneath. Lesions may spread around the circumference of the trunk slowly girdling the tree.
Phytophthora will result in overall poor tree health, a thinner canopy and failure to make new growth. When roots are directly affected, the surface of the root will become soft and appear water-soaked and discoloured. Finally, for citrus trees specifically, if you have citrus root weevil present on your tree as well, these symptoms will progress quicker and your tree will become damaged much faster.
Treatment of Phytophthora
Unfortunately, Phytophthora is not a very treatable problem. If you do notice the symptoms above in your citrus tree early, there are a couple of ways you can reduce the damage. Examining the soil line for root rot or any water-logging should be the first step. If the soil is very moist, replace it and let the crown tissue of your tree dry out.
If any gummosis has begun to occur on the branches or trunk, the best thing to do is carefully cut away the infected areas to reduce spreading.
Prevention of citrus root rot and gummosis
The best way to prevent this fungal disease from harming your citrus trees and other plants is simply by being clean, tidy and keeping a close eye on your garden. Having good water management is the top priority for reducing the threat of Phytophthora. Here are a couple of tips for water management and general garden maintenance that can help your garden thrive without any Phytophthora problems:
- Avoid prolonged soil saturation. This includes standing water around tree bases and over-irrigating your garden. Having a mist irrigation system or irrigation that only sprays the soil may be the most helpful.
- Provide good soil drainage for vegetable, fruit and other orchard plants. When there is extensive wet weather or moist conditions, you do not want the roots or crown of a plant to remain wet for more than 4 hours. It generally take 4-8 hours for Phytophthora to infect a plant.
- Avoid installing irrigated turf around the base of trees.
- Remove all weeds from susceptible plants.
- Having raised garden beds for vegetable plants may be helpful, as they provide great soil drainage.
- Finally, group plants based on their watering needs in your garden. This is to avoid waterlogging soil and over-watering plants that do not need it.
You may also like:
How to get the most out of your citrus plants
How do you fix yellow leaves on a lemon tree
Do this now to prevent citrus leafminer on your trees
How to stop citrus gall wasps from destroying your trees
Related stories
Native ad body.
Native ad body.
Native ad body.
