Help - Serious spreading Amorph disease

From: Adam Black epiphyte1 at earthlink.net> on 2006.07.08 at 18:05:21(14395) We are suddenly having a severe problem with the Amorphophallus species at the botanical gardens where I work. We are seeing a localized rotting of the base of the petiole an inch or two above the soil line that turns the petiole base to jelly and topples the leaf. It is affecting all three species we have - A. konjac, A. bulbifer, and A. paeoniifolius, and is occurring in various areas of the gardens that are seperated by a considerable distance and have been otherwise healthy in thier locations in the ground for years. I started noticing it in the konjacs and the bulbifers a month or so ago shortly after they put up thier leaves, and the rate of loss has escalated from there. I just now noticed on the late emerging paeoniifolius that most of them have early signs of this infection. I am by no means an expert on fungi, but there are several different colors of fungus on the affected areas, but I am not sure if this is secondary or not. The infection starts out as a brown patch on the base of the petiole a few inches above the soil/leaf litter line, and this progresses around the petiole and inward, but does not spread up or down the petiole from that point. I dug up one corm from an infected A. bulbifer and it appeared shrunken in and clearly unhealthy, felt softer than a healthy corm but no external evidence of rot was evident. I did not cut it open to see what it looked like inside, but plan to on another specimen this week.The base of the petiole below where the leaf had rotted off was still healthy in appearance and firmly connected to the corm. Curiously, I have yet to see it affect any similar aroids growing side-by-side with affected Amorphs in the gardens including Typhonium venosum (of which we have many plants), Gonatopus bovinii, Remusatia vivipera, and our native Arisaema triphyllum and jillions of Arisaema dracontium. The Amorphs affected include both potted specimens and those situated in the ground for years, and among the potted specimens some affected plants are in a greenhouse with controlled watering, while other potted plants are exposed to the weather in addition to supplemental irrigation. I am keeping a closer eye on it now, but the infection appears to spread and rot through the petiole relatively quickly, so that the leaf itself still looks unstressed and perfectly healthy after it has rotted off. I have only worked here since this past winter, but the gardens director remembers a few Amorphs having this problem last year but didn't think much of it, as the hundreds of others in our mass plantings looked fine. If I had to guess now, I would say we have lost about 60 or so plants with about as many showing the early stages of the infection. It also seems to affect our mid to largest size specimens rather than the smaller plants. Has anybody seen this before? Any recommendations? I am going to try a fungicide this week, but with the huge number of plants we have spread out all over our 60+ acre gardens, I am worried about how effective any methods will be in controlling this. If anyone is interested I can email photos of affected plants in various stages of infection. Thanks Adam +More _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l

From: "Peter Matthews" pjm at gol.com> on 2006.07.09 at 04:15:43(14396) Dear Adam, Did your garden recenty import Amorphophallus specimens from SE Asia or other places where the genus is native? If you could identify possible geographical sources, this might help narrow down the search for a cause. Also, I wonder if there are any insects that lay their eggs in the lower petiole area? In theory, a newly spreading insect might spread a new or existing fungus. I do not know of such happening in Araceae, but it is conceivable. Taro has taro-specific planthoppers (Delphacidae) that lay eggs in the lower petiole, and they are spread with planting materials when the petioles are kept attached to the corm. There might be planthoppers that are specific to Amorphophallus (this is speculation). If you want, I could try to contacting konyakku researchers here in Japan. There would certainly be interested in the outbreak you describe, even if it is something new for them. Or they might immediately recognise what is happening to your plants. There is a lot of experience with intensive production of Amorphophallus here in Japan. Good luck... Peter Matthews +More On 8/7/2006, "Adam Black" wrote: > >We are suddenly having a severe problem with the Amorphophallus species >at the botanical gardens where I work. We are seeing a localized rotting >of the base of the petiole an inch or two above the soil line that turns >the petiole base to jelly and topples the leaf. It is affecting all >three species we have - A. konjac, A. bulbifer, and A. paeoniifolius, >and is occurring in various areas of the gardens that are seperated by a >considerable distance and have been otherwise healthy in thier locations >in the ground for years. I started noticing it in the konjacs and the >bulbifers a month or so ago shortly after they put up thier leaves, and >the rate of loss has escalated from there. I just now noticed on the >late emerging paeoniifolius that most of them have early signs of this >infection. I am by no means an expert on fungi, but there are several >different colors of fungus on the affected areas, but I am not sure if >this is secondary or not. The infection starts out as a brown patch on >the base of the petiole a few inches above the soil/leaf litter line, >and this progresses around the petiole and inward, but does not spread >up or down the petiole from that point. I dug up one corm from an >infected A. bulbifer and it appeared shrunken in and clearly unhealthy, >felt softer than a healthy corm but no external evidence of rot was >evident. I did not cut it open to see what it looked like inside, but >plan to on another specimen this week.The base of the petiole below >where the leaf had rotted off was still healthy in appearance and firmly >connected to the corm. > >Curiously, I have yet to see it affect any similar aroids growing >side-by-side with affected Amorphs in the gardens including Typhonium >venosum (of which we have many plants), Gonatopus bovinii, Remusatia >vivipera, and our native Arisaema triphyllum and jillions of Arisaema >dracontium. The Amorphs affected include both potted specimens and those >situated in the ground for years, and among the potted specimens some >affected plants are in a greenhouse with controlled watering, while >other potted plants are exposed to the weather in addition to >supplemental irrigation. I am keeping a closer eye on it now, but the >infection appears to spread and rot through the petiole relatively >quickly, so that the leaf itself still looks unstressed and perfectly >healthy after it has rotted off. I have only worked here since this past >winter, but the gardens director remembers a few Amorphs having this >problem last year but didn't think much of it, as the hundreds of others >in our mass plantings looked fine. If I had to guess now, I would say we >have lost about 60 or so plants with about as many showing the early >stages of the infection. It also seems to affect our mid to largest size >specimens rather than the smaller plants. > >Has anybody seen this before? Any recommendations? I am going to try a >fungicide this week, but with the huge number of plants we have spread >out all over our 60+ acre gardens, I am worried about how effective any >methods will be in controlling this. If anyone is interested I can email >photos of affected plants in various stages of infection. > >Thanks > >Adam > > >_______________________________________________ >Aroid-l mailing list >Aroid-l@gizmoworks.com >http://www.gizmoworks.com/mailman/listinfo/aroid-l > _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l

From: Tony Avent tony at plantdelights.com> on 2006.07.09 at 14:53:28(14397) Adam: I'd venture a guess that your culprit is a bacterial soft rot, Erwinia. If so, fungicides are useless. I have seen this devastate collections of certain amorphophallus species under certain conditions. It seems to be worse when there is little air movement, lots of moisture, and high humidity. I have even heard theories that it can be spread by the hands of those who have handled tobacco or tobacco products. You will find many references by using a Google search. Tony Avent +More Plant Delights Nursery @ Juniper Level Botanic Garden 9241 Sauls Road Raleigh, North Carolina 27603 USA Minimum Winter Temps 0-5 F Maximum Summer Temps 95-105F USDA Hardiness Zone 7b email tony@plantdelights.com website http://www.plantdelights.com phone 919 772-4794 fax 919 772-4752 "I consider every plant hardy until I have killed it myself...at least three times" - Avent Adam Black wrote: We are suddenly having a severe problem with the Amorphophallus species at the botanical gardens where I work. We are seeing a localized rotting of the base of the petiole an inch or two above the soil line that turns the petiole base to jelly and topples the leaf. It is affecting all three species we have - A. konjac, A. bulbifer, and A. paeoniifolius, and is occurring in various areas of the gardens that are seperated by a considerable distance and have been otherwise healthy in thier locations in the ground for years. I started noticing it in the konjacs and the bulbifers a month or so ago shortly after they put up thier leaves, and the rate of loss has escalated from there. I just now noticed on the late emerging paeoniifolius that most of them have early signs of this infection. I am by no means an expert on fungi, but there are several different colors of fungus on the affected areas, but I am not sure if this is secondary or not. The infection starts out as a brown patch on the base of the petiole a few inches above the soil/leaf litter line, and this progresses around the petiole and inward, but does not spread up or down the petiole from that point. I dug up one corm from an infected A. bulbifer and it appeared shrunken in and clearly unhealthy, felt softer than a healthy corm but no external evidence of rot was evident. I did not cut it open to see what it looked like inside, but plan to on another specimen this week.The base of the petiole below where the leaf had rotted off was still healthy in appearance and firmly connected to the corm. Curiously, I have yet to see it affect any similar aroids growing side-by-side with affected Amorphs in the gardens including Typhonium venosum (of which we have many plants), Gonatopus bovinii, Remusatia vivipera, and our native Arisaema triphyllum and jillions of Arisaema dracontium. The Amorphs affected include both potted specimens and those situated in the ground for years, and among the potted specimens some affected plants are in a greenhouse with controlled watering, while other potted plants are exposed to the weather in addition to supplemental irrigation. I am keeping a closer eye on it now, but the infection appears to spread and rot through the petiole relatively quickly, so that the leaf itself still looks unstressed and perfectly healthy after it has rotted off. I have only worked here since this past winter, but the gardens director remembers a few Amorphs having this problem last year but didn't think much of it, as the hundreds of others in our mass plantings looked fine. If I had to guess now, I would say we have lost about 60 or so plants with about as many showing the early stages of the infection. It also seems to affect our mid to largest size specimens rather than the smaller plants. Has anybody seen this before? Any recommendations? I am going to try a fungicide this week, but with the huge number of plants we have spread out all over our 60+ acre gardens, I am worried about how effective any methods will be in controlling this. If anyone is interested I can email photos of affected plants in various stages of infection. Thanks Adam _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l

From: Susan B honeybunny442 at yahoo.com> on 2006.07.10 at 02:12:43(14399) Hi Adam, I lost my entire crop of konjacs to this about 5 years ago. It affected the konjacs while other Amorphs right next to them had no problems! I've also lost a significant amount of Zantedeschia to soft rot/Erwinia 2 years ago. The plants looked just fine, until suddenly they toppled over at the base. The petioles looked like they melted. I've also seen it affect cut flowers- the plant looked fine, the flower was picked and put into water in a vase. The next day the petiole would have literally dissolved all the way up to the spathe, which would look OK for a little while and then it too would start to "melt". My soft rot/Erwinia, which, by the way, I understand is two different diseases but work together; seemed different from your plant's symptoms. First, the rot would progress up the petiole or down to the tuber. I could pull the bloom and leaves right out of the ground with no effort. Second, it has a very awful, rotten, stinky smell. The tubers would also be affected, with large sections rotting off. Erwinia is a bacterial disease (if I remember correctly), it is very contagious and can be carried on feet from one site to another. Phyton 20, a copper based formula, is said to prevent it, but bulbs must be sprayed before planting. I believe if it affects an area you are not supposed to use that soil again because it is infected. I did rescue a few of my tubers that weren't too badly affected, I used a water hose to vigorously spray them until all the mush washed away. Then I dried the tubers in the sun/ air as much as possible. Some of them were viable the next year, I only had about 3 plants with it last year as opposed to maybe a hundred the year before. Truly a heartbreaking disease. I wish you luck with it. Since your tubers seem to be OK, you may have some other disease or pest going on.... Susan B +More __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l

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