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Rhys starts with ... I've recently noticed some new branches on my avocado going black...i pruned them off, but have now noticed a section of the trunk going black as well. Some of the leaves are also a bit funny. It's been in a relatively sheltered position for most of summer, so i'm pretty confident it's not sunburn, and i suspect it's anthracnose, but before i start spraying with anything, i thought i'd ask around to see what other people thought.
| About the Author Getafix Newcastle 12th March 2011 11:53pm #UserID: 3112 Posts: 86 View All Getafix's Edible Fruit Trees |
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About the Author Wayne Mackay QLD 13th March 2011 7:27am #UserID: 338 Posts: 908 View All Wayne's Edible Fruit Trees |
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Brendan says... Hi Rhys, It wouldn't hurt to spray with copper oxychloride & mancozeb plus, 30g of each, in 4½ litres water, plus a 'good' wetting agent, at least 30ml. Spray once a week for 4 weeks, then once a month untill it's gone. Photo 3 looks like it's lacking phosphorus (P) fertilizer. Could be the start of either Anthracnose or Phytophthora (dying branches), the above spray should fix it. | About the Author Brendan Mackay, Q 13th March 2011 9:08am #UserID: 1947 Posts: 1722 View All Brendan's Edible Fruit Trees |
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Original Post was last edited: 13th March 2011 9:14am | ||||||||||
Rhys says... Thanks guys. Brendan, how crucial is the mancozeb component. I already have some copper oxychloride, but wondering whether i should go and get the mancozeb as well. Would it be ok to spray with the copper initially and then add in the mancozeb when i get a chance to buy some. As for the wetting agent, i have some Amgrow Wettasoil liquid which i'm assuming should be OK for the job. I've been giving it some seasol, but it probably is due for a feed as well...see how we go! Thanks again | About the Author Getafix Newcastle 13th March 2011 12:43pm #UserID: 3112 Posts: 86 View All Getafix's Edible Fruit Trees |
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About the Author Wayne Mackay QLD 13th March 2011 1:18pm #UserID: 338 Posts: 908 View All Wayne's Edible Fruit Trees |
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Brendan says... Hi Rhys, Please DON"T use Wettersoil as a wetting agent, it's not made for that. Bunnings here sell 'Spredmax' in a 200ml bottle. Or use Spreadwell, Agral etc. (I use Activator). Yeah, as Wayne says, the wetter is the key, BUT, I would get the mancozeb plus asap. Try the Copper Oxychloride first if you have to, but add some Spredmax, say 30ml to the 4½ L of water. | About the Author Brendan Mackay, Q 14th March 2011 8:46am #UserID: 1947 Posts: 1722 View All Brendan's Edible Fruit Trees |
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Original Post was last edited: 14th March 2011 8:47am | ||||||||||
About the Author Peter36 Perth 15th March 2011 11:32am #UserID: 5034 Posts: 213 View All Peter36's Edible Fruit Trees |
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Rhys says... Thanks again, Peter, yes i was a bit worried about Phytophthora but when i read the NSW DPI document about avocado diseases, anthracnose did seem to be a better fit, so we'll see. Brendan...ummm...how bad would it be...er, hypothetically...if, say, i had already used the wettasoil...hypothetically!?!? I will go and buy some proper stuff tomorrow! The other thing i was wondering, it's a pretty small tree, and takes less than 500ml to wet the whole thing, but only making up 500ml involves some pretty small volumes/weights, so i was wondering how long the mix would last if i made up a bigger batch, or is it best to make it fresh each time? | About the Author Getafix Newcastle 15th March 2011 9:06pm #UserID: 3112 Posts: 86 View All Getafix's Edible Fruit Trees |
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Brendan says... Hi Rhys, I'm fairly sure it says on the wettersoil bottle, if it's sprayed on leaves etc, to wash it off? It's actually used to drench the ground and make the soil around the roots 'wetter'. Would have to disagree with Peter about phytophthora, it has killed at least 3 avocado trees of mine, luckily they were 'only' seed grown, what happens is the leaves all start to droop, then they fall off, then the branches start going black from the top down (not the other way 'round). I would only mix the amount of spray needed for say one week :-) Just remembered, you can use 1/3 cup of Lux flakes, dissolved in some hot water, for your 'wetter'. Just add that to 4½ litres of water, copper oxy etc., but that brew doesn't keep very long :-( Just mix up a smaller amount. | About the Author Brendan Mackay, Q 16th March 2011 9:44am #UserID: 1947 Posts: 1722 View All Brendan's Edible Fruit Trees |
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Original Post was last edited: 16th March 2011 9:50am | ||||||||||
Peter says... To make a simple test for Phytophthora: 1) Dig up some soil with some of the avocado roots and put it in a take away container about one third full 2) Fill up the container with rainwater 3) Create a clean water surface by pushing aside floating particles and keep them in place with some plastic stuff (not metal)such as a cut piece of shadecloth etc. 4) Put some soft leaves (not hardened old ones) on the watersurface (some leaves work better than others). The container should be at room temperature. Within 1 to 7 days, mostly after 2 to 3 days the leaves turn rapidly brown to black all over. This is only an indicator, but a quite good one as only a few other root pathogens make swimming spores which then swim towards the watersurface to infect the leaves. Therefore point 3) is important to have no soil particles to touch the leaves - otherwise all sorts of other organisms in the particles invade the leaves. If it takes many days for a discolured leave area to expand then it is most likely not Phytophthora.
| About the Author Peter36 Perth 16th March 2011 10:38am #UserID: 5034 Posts: 213 View All Peter36's Edible Fruit Trees |
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Rhys says... Thanks guys. Brendan...with the wettasoil, it actually says on it something like that it wouldn't harm plants, grass, animals etc which was why i initially thought it would be OK...anyway, i have now bought some spredmax. The lesion on the main trunk eventually "ringbarked" the tree and the top section died off, but there has been quite a few new shoots sprout below this spot so i am hopeful the plant will survive. One other question i had was, given that in its current location it is quite sheltered and gets no direct rain on to it, would i still need to spray as often. I'm assuming that in the absence of rain that the residue would hang around on the leaves longer. Is my assumption correct? | About the Author Getafix Newcastle 21st April 2011 9:51pm #UserID: 3112 Posts: 86 View All Getafix's Edible Fruit Trees |
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Brendan says... Hi Rhys, I'd cut the dead bit off and spray again weekly for 3 or 4 weeks. Then, once a month. Actually, the rain encourages the anthracnose to spread, especially if the lower branches are close to the ground, the rain can splash the spores onto the low branches. Another good idea is to spray the trunk and the ground under the canopy spread, to kill the anthracnose spores. I'd add mancozeb to the copper oxychloride and wetter. Try adding 30ml of wetter (or more) to the 4½ litres of spray. Fertilize it with sulphate of potash, that will harden-up the plant tissue, and I'd give it some gypsum as well. Btw, what type of avo is it? | About the Author Brendan Mackay, Q 22nd April 2011 7:39am #UserID: 1947 Posts: 1722 View All Brendan's Edible Fruit Trees |
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Original Post was last edited: 22nd April 2011 7:55am | ||||||||||
Rhys says... Thanks Brendan...yes, i've already cut the top section off, and so far so good. I've been giving it the occasional drink with seasol and powerfeed, so hopefully those two should give enough potassium. Does it need gypsum given it's in a pot? It is a Secondo avocado bought from Daleys last year. | About the Author Getafix Newcastle 23rd April 2011 10:07pm #UserID: 3112 Posts: 86 View All Getafix's Edible Fruit Trees |
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About the Author Brendan Mackay, Q 24th April 2011 7:01am #UserID: 1947 Posts: 1722 View All Brendan's Edible Fruit Trees |
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About the Author Avacodo leaf dis dorothy1924 2nd June 2016 5:42pm #UserID: 14020 Posts: 1 View All Avacodo leaf dis's Edible Fruit Trees |
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