Disease · Peach, almond and broccoli
Xanthomonas: the bacteria that arrive with the rain
Xanthomonas arboricola pv. pruni · X. campestris pv. campestris
Two bacteria of the same group: one on stone fruit, the other on brassicas. They move with water and tools. We fly and mark the most damaged zones, so you can check them and send samples.
We have not flown this problem ourselves yet. We work it out with you, on your field.
The problem
Bacteria that travel with water
On peach and almond (bacterial spot), angular spots appear on the leaf, first translucent and then dark; they sometimes fall out and leave holes. On the fruit, sunken spots that crack and ooze gum. It likes warmth with mild, frequent rain, wind and dew. Plant health rules in many countries cover nursery trees of stone fruit, so buy certified plants.
On broccoli and other brassicas it is black rot: the leaf turns yellow in a V shape from the edge, with black veins. It arrives mostly with seed, transplants and residues of the previous crop. In cabbage the whole crop can be lost, although in a temperate climate it rarely kills the whole plant.
How it works
A flight to know where to look
1
We fly
In fruit trees, at the end of spring or in summer, when there is leaf drop or weak trees after a wet spell; in brassicas, when yellow or dry plants appear.
2
We send you the map
Zones with leaf drop or dry plants. The spots are millimetres across and cannot be seen from the drone. It is confirmed by laboratory testing, because it is easily mistaken for other bacteria.
3
You act
You remove what is diseased, disinfect tools and, in brassicas, rotate for several years without crucifers (the cabbage family).
Where it shows up
Where it appears
- Peach
- Almond
- Broccoli
On stone fruit it is not present everywhere. Black rot affects all cultivated brassicas, cabbage and turnip included.
What farmers ask us
Xanthomonas: field questions
Is it a quarantine disease?
In stone fruit it is covered by plant health rules for nursery material in many countries. Buy certified plants and check the rules where you farm.
How long should I rotate in brassicas?
Several years without crucifers; your adviser will tell you how many for your field.
How do I keep it out of brassicas?
With healthy seed and transplants. Treating the seed with hot water lowers infection, but it needs precise conditions and can cost some germination. Better left to the seed supplier.
Know someone this would help?
Send them this page. If they have xanthomonas in their fields, you save them some searching.