Stigmatomycosis
| Stigmatomycosis | |
|---|---|
| Causal agents | Ashbya gossypii,Eremothecium coryli,Aureobasidium pullulans |
| Hosts | cotton,soybean,pecan,pomegranate,citrus,pistachio |
| Vectors | hemipteraninsects of the familiesPentatomidaeandCoreidae |
| EPPO Code | NMATGO |
| Distribution | Greece, Iran, Russia, California |
Stigmatomycosisis a fungal disease that occurs in a number of crops, such ascotton,soybean,pecan,pomegranate,citrus,andpistachio.It has been reported on pistachio inGreece,Iran,Russia,and is frequently a problem in California pistachio orchards severely infested byhemipteraninsects.In a 1989 survey inCalifornia,fruit with stigmatomycosis were found in 90% of samples collected from late June to mid-September and from all growing areas.
Symptoms[edit]
Stigmatomycosis is characterized by a wet, smelly, rancid, slimykernel.Kernels with stigmatomycosis can be 1) small, dark green and partially developed with a brownfuniculus,2) well-developed, dark green and rancid, or 3) full-sized but abnormal, being white or light yellow and jelly-like, with a lobed appearance. In contrast, symptoms of kernelnecrosis,which is caused by largehemipterans,are dry, punky, brown areas in the kernel. Sometimes, kernel necrosis and stigmatomycosis symptoms can be present in the same fruit.[citation needed]
Causal organisms[edit]
Stigmatomycosis is caused by thefilamentous fungiAshbya gossypii,Eremothecium coryli(syn.Nematospora coryli), andAureobasidium pullulans.All of them belong to the phylum ofascomycetes[citation needed]
Disease cycle and epidemiology[edit]
The fungi causing stigmatomycosis are associated withhemipteraninsects of the stinkbug familiesPentatomidaeandCoreidae.Hemipterans are commonpestsinpistachioorchards, and up to ten species have been found inCaliforniapistachio orchards. Three common stinkbug pests,Thyanta pallidovirens(Western red-shouldered stinkbug),Chlorochroa uhleri,Chlorochroa ligata,and aleaffootedbug,Leptoglossus clypealis(Coreidae), experimentally transmittedE. coryli,which caused typicalsymptomsof stigmatomycosis in pistachiokernels.Symptoms first appear in late June after pistachio shells have hardened, but the disease becomes frequent in July through September, a period that coincides with kernel development. Smaller hemipterans, such asLygusandCalocoris,may carry but not transmit thepathogensbecause they are unable to puncture the firm fruitpericarpafter the second part of May. Stigmatomycosis and kernelnecrosisare worse in orchards irrigated bysprinklersthan in those irrigated by drip,microjets,or flood. This suggests either greater humidity requirements for infection, more activity of hemipterans in sprinkler-irrigated orchards, or more abundant pathogenpropagules.[citation needed]
Control[edit]
Fungicidesdo not control stigmatomycosis butinsecticidesreduce hemipteranvectorpopulations and the incidence of stigmatomycosis.[citation needed]
References[edit]
- Themis J. Michailides.""Above ground fungal diseases", Chapter 27 "(PDF).[dead link]