| Scientific name|
- Dickeya spp. pineapple infecting strains (formerly Erwinia chrysanthemi)
- Internationally, caused by Dickeya spp. complex, which consists of several closely related species.
- Different Dickeya species can infect the same type of host in different countries.
- Pineapple infecting strains of Dickeya spp. were previously known as Erwinia chrysanthemi.
- Bacterial heart rot and fruit collapse of pineapple are 2 separate diseases caused by a single species of bacteria belonging to the Dickeya spp complex.
- In Queensland, the diseases are caused by the species Dickeya zeae.
| Other names|
In bacterial heart rot:
- infection usually occurs on leaves of young plants 4 to 8 months after planting.
- under optimum conditions, disease development takes from 1 to 2 weeks after initial symptoms.
In fruit collapse:
- infection occurs through flowers.
- symptoms remain latent until 2 to 3 weeks before ripening.
- infected fruits collapse rapidly in field conditions.
- Has recently been detected in Queensland and the Northern Territory, Australia.
- Also found in Brazil, Costa Rica, Hawaii, Malaysia, the Philippines.
- Dickey sp. is a motile gram-negative plant pathogenic bacterium.
- Bacterium persists in host plant debris in soil.
- Infects host plants at the site of an injury or wound.
- Following infection, it multiplies, moves through vascular system and damages several parts of the host.
- Exudates from diseased plants or fruit provide secondary source of infection for nearby plants.
- After harvesting, host debris in soils acts as source of inoculum for next host crop.
- Many Dickey spp. can survive in host-free soil, river and irrigation water for several months by which it disseminates and infects new hosts.
- Bacterium can also remain latent in the host plant, spread long distances and act as primary source of infection for new location
| Crops affected|
- Pineapple, possibly other non-crop plants
- Fruit shells become olive green in colour.
- Fruit exudes juice and releases gas due to fermentation.
- Fruits collapse 2 to 3 weeks before ripening.
- Blisters appear consisting of gas filled brown streaks on the leaf.
- Water soaked lesions occur on the white basal part of leaves (in the centre whorl).
- Cavities develop within the fruit.
- Dickeya spp. are reported to cause soft rot in a wide range of hosts.
- Plant diseases caused by species of Dickeya result in significant losses of many economic crops and ornamentals plants around the world.
- Crop losses of up to 40% have been reported for bacterial heart rot and fruit collapse diseases of pineapple in Malaysia.
- A severe outbreak of the disease could significantly impact employment and livelihood of pineapple growers, and sustainability of the pineapple industry.
Can spread locally and distant through infected plant material, plant debris, the wind, wind-blown rain, insects, soil, irrigation water and contaminated machinery.
- Vegetative growth and fruiting stages of host plant present high risk of infection.
- Environmental factors like high humidity, warm temperatures (25o to 30oC) and rain significantly enhance impact of the diseases locally.
|Monitoring and action|
Inspect fields regularly for symptoms of the diseases, typically:
- central whorl of leaves in young plants
- soft rot on mature fruit of pineapple.
Remove infected plants immediately.
Report symptoms to Biosecurity Queensland 13 25 23.
- If you see symptoms consistent with bacterial heart rot/fruit collapse call the Exotic Plant Pest Hotline on 1800 084 881 or Biosecurity Queensland 13 25 23.
|Diseases can spread through asymptomatic planting materials. Therefore, it is important to have quarantine restrictions on the movement of planting materials from infested areas.|
| More information|