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BigC starts with ... I have a mature (20 yrs+/-, 6m+/- tall) avocado tree (I think Fuerte) which is currently fruiting, but... 1. some fruit, which generally fall to ground, have large brown blotches (2-3cm dia) that quickly spreads over the fruit. See pictures 2. leaves are dry & brown from tip up to about half way, with leaves in lower portion of the canopy more affected than upper portion. See pictures. A larger Avo tree (I think a different variety - produces small number of larger pear shaped fruit) just 4m away has healthy green leaves all over but no fruit (This one is erratic) Soil is sandy free draining. The tree has access to ample water (from bore) - but how much and how often I should water is another question (currently 3 times/wk for 30 min's) I have searched web all over but can't confirm the diagnosis (anthracnose, too much/too little water, fungus, ...) Any advice will be greatly appreciated. Thanks in advance
| About the Author Col Leeming, WA 9th December 2010 2:47pm #UserID: 4632 Posts: 3 View All Col's Edible Fruit Trees |
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amanda says... Don't know about the fruit BigC - but when did you last get yor bore water tested? Pic 2 looks like salt damage - and Avo's hate salinity. I would start giving it regular feeds of seasol, some gyspum (once) and start using tap/scheme water until you get the bore tested maybe? Do u have any other fruit trees? Also - what have you been feeding the tree? (another possibility is potassium deficiency) | About the Author amanda19 Geraldton Mid West WA 9th December 2010 6:06pm #UserID: 2309 Posts: 4607 View All amanda19's Edible Fruit Trees |
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Brendan says... G'day BigC, looks like a classic case of Anthracnose to me. You need to spray with copper oxychloride 30g, Mancozeb plus 30g in 4½ litres of water. Must add a 'good' wetting agent, say 30ml as well. Probably too late for this seasons crop, but start spraying just before flowering, when the flowers open, don't add the copper. once small fruit has formed, add the copper again and spray weekly for 4 weeks, then monthly until harvest. I'd give it 4 handfuls of gypsum per sq m, and superphosphate at 1 handful sq m under the canopy spread. Some potash would not hurt either. Mulch heavily out to and past the dripline keeping it 200mm from the trunk. I'd prune a third off the top too. Have the trees been under stress lately? or, has the fruit been on the tree a long time? This can make the fruit go black too, but, I stil say it's anthracnose. | About the Author Brendan Mackay, Q 10th December 2010 8:07am #UserID: 1947 Posts: 1722 View All Brendan's Edible Fruit Trees |
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Original Post was last edited: 10th December 2010 8:24am | |||||||
| About the Author Col Leeming, WA 13th December 2010 2:46am #UserID: 4632 Posts: 3 View All Col's Edible Fruit Trees |
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amanda says... Hi Big C - I am glad Brendan said anthracnose too - I am not very familiar with it (except on the C grade mangoes we often get...) but I was wondering about the same thing. But - and don't quote me on this - I have a general impression that fruit trees (in WA at least) don't do well on bore water. Veg can take more salinity because they are a quicker crop. I am aware that many commercial fruit growers don't use bore water. Bore water also suffers from seasonal changes. I would still treat as Brendan said - and get your bore water tested also. Most fruit and nut trees don't handle salt very well. It may be ok to use - or you may need to modify your watering and feeding practices. | About the Author amanda19 Geraldton Mid West WA 13th December 2010 8:53pm #UserID: 2309 Posts: 4607 View All amanda19's Edible Fruit Trees |
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Josh says... This actually could be a Calcium deficiency as well. Anthracnose and Calcium deficiency look somewhat similar and have a correlation, since damaged roots of calcium deficient plants become prone to infection by bacteria and fungi. A Calcium deficiency will cause what's called "Blossom End Rot". This is where the base of the fruit looks rotted which is what appears to be happening in your pictures. My recommendation is to get the water AND the soil tested to see if your calcium range is within the normal range for your area or pH of soil. Let me know what comes about. | About the Author Josh3 Las Cruces 1st April 2011 11:26am #UserID: 5132 Posts: 1 View All Josh3's Edible Fruit Trees |
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Jason says... My Avocados get rotten from the bottom but only once they are way past the ideal point of being ripe and the roots have actually started to exit the fruit. At that stage they drop to the ground and start growing. These ones don't look to be that ripe?, I can't see any holes the roots have punched in the bottom anyway | About the Author Jason Portland 1st April 2011 11:30am #UserID: 637 Posts: 1217 View All Jason's Edible Fruit Trees |
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Peter says... Anthracnose I'd say as well. Its good that Josh also mentioned 'Blossom end root' and I looked just now in the Avocado book by Hofman which mentions Calcium deficiency as a cause for blackening of Avo fruit beginning from the fruitstem. To see if it is Anthracnose you could do two things: 1) You could check if you also can see black branches as Anthracnose also grows through branches. 2) Cut of a small healthy and green branch and put in a glass of water. In the middle cut wounds in the stem and then apply the black stuff from your fruit on these wounds and seal it to prevent drying out (such as gladwrap). If it is the Anthracnose fungus, then it will grow through the wounds into to stem and move upwards and downwards, so after two weeks or so you will have a black stem too. Just one question to all about the leaves in the pic. I have the same problem and I also try to do the minimum effort. It looks like only old leaves are saltdamaged and at the same time new, healthy leaves form anyway. So can we get away with it not doing too much? | About the Author Peter36 Perth 1st April 2011 3:28pm #UserID: 5034 Posts: 213 View All Peter36's Edible Fruit Trees |
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