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  • Black Spots on Apples???

    I have got a small apple tree (it is a grafted one with two varieties) and some (not all) the apples have got small black spots on them. I've attached a picture. They aren't pitted or rough, in fact, they feel the same as the rest of the apple. Do you know what it is and what can be done to avoid it getting to the rest of the apples? I've picked off the ones with the black spots (hopefully the right thing to do) as there were plenty of apples on the tree anyway so when I thinned them out I made sure any with black spots were the first to go.
    Attached Files

  • #2
    Dunno really, but googled it and found this:

    Black Spot on Apples and Pears - Hortwatch Library

    Scary!

    Good luck
    If the river hasn't reached the top of your step, DON'T PANIC!

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    • #3
      I sprayed it with fungicide anyway. The leaves don't have the patches for apple scab / black spot. They look quite healthy. Let's hope the fungicide combined with picking off the spotty apples will help.

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      • #4
        They don't look like apples, just the little unfertilised ones that fall off anyway. Its June drop time too so your tree may be dumping some of its own accord.
        I'm sure someone who knows what they're talking about will be along soon -( no offence intended PnK

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        • #5
          It is always tremendously helpful to know someone's location when giving advice.

          My guess is that it's scab - a combination of wet weather and a variety which doesn't have sufficicent resistance (i.e. a fairly common variety), or a specific apple variety which is grown in large numbers in your area (hence there has been a long-term build-up of diseases which have had plenty of time to find ways round a tree's resistance).

          Infections which are already present won't be cured. It is likely that the brown (dead) bits will not grow properly as the apples get bigger which often results in the skin splitting and the fruit rotting on the tree.
          .

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          • #6
            Here's a link to a nice picture of what can happen:

            BEV1595- APPLE FRUIT SPLIT ON APPLE : Asset Details -Garden World Images

            As I said: once infected the brown bit is already dead and wll not grow properly (hence splitting).
            On very susceptible varieties, fungicide (<shudder>) needs to be applied immediately after any period of several hours of rain.
            The link provided by PnQ above gives a nice table of wet period v temperature. Periods which coudl result in scab infection are also known as "Mills periods".
            A more detailed Mills table here, which shows that symptoms appear a couple of weeks after infection has occured:

            Untitled Document



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            • #7
              I have gotten rid of all the ones with spots on so I'm hoping the rest will be ok. I shall have to take my chances and see what happens now.

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              • #8
                Well wherever it came from, it'll probably come back from in the future. The spores may also be scattered around the tree from rain splash and fallen leaves.

                Along with not mentioning location, you haven't mentioned the variety which you're growing.
                These could have a large influence on whether it's likely to be transient for this wet year only, or whether you're building epidemic proportions of attack for subsequent years.

                The problem with spraying against scab, is that the fungicide also kills "good fungi" which expose the tree to other attacks from other fungi (which the "good fungi" would normally outcompete and drive-out). So once spraying routines have begun, if can become a vicious circle - otherwise the consequence is a very diseased tree for a few years after spraying is stopped, until the "good fungi" find their way back to it (carried by wind or rain splash).

                It is quite common for newly planted trees to suffer from diseases because they were sprayed at the nursery from which they came (and, of course, the nursery was an ideal breeding ground for diseases with large numbers of trees crowded together).

                Of course, some trees - the well-known varieties you find in the supermarkets or farm shops - are often quite very prone to diseases; especially scab.

                For curiosity: I have a lot of rare varieties and despite the unprecedented heavy rain we've seen (barely a day without rain for three months and we've already had about two years worth of rain so far this year!), yet the rare varieties have no fruit scab at all, and only minor leaf scab which I can only find on the odd leaf, if I look very closely. Quite impressive.

                On the other hand, my James Grieve and Egremont Russet (two fairly common varieties) have both died from an overwhelming attack of canker, the likes of which I've never seen or heard of.
                Last edited by FB.; 08-06-2012, 10:02 PM.
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                • #9
                  Now you're making me nervous about my two new apple trees that are not yet planted. Off to do a search on here to find out what my worst problems are likely to be.
                  Ali

                  My blog: feral007.com/countrylife/

                  Some days it's hardly worth chewing through the restraints!

                  One bit of old folklore wisdom says to plant tomatoes when the soil is warm enough to sit on with bare buttocks. In surburban areas, use the back of your wrist. Jackie French

                  Member of the Eastern Branch of the Darn Under Nutter's Club

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                  • #10
                    Originally posted by veggiechicken View Post
                    They don't look like apples, just the little unfertilised ones that fall off anyway. Its June drop time too so your tree may be dumping some of its own accord.
                    I'm sure someone who knows what they're talking about will be along soon -( no offence intended PnK
                    None taken! I was relying on FB coming along and giving us the real gen!!!
                    If the river hasn't reached the top of your step, DON'T PANIC!

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                    • #11
                      Originally posted by Feral007 View Post
                      Now you're making me nervous about my two new apple trees that are not yet planted. Off to do a search on here to find out what my worst problems are likely to be.
                      If your apple trees are in Australia, there will be different strains of disease out there, which are adapted to attack your local varieties but which aren't adapted to attack more unusual varieties.

                      So if I were you, I'd take English disease data with a bit of caution.

                      In my experience, every apple variety is disease resistant. Yes, you read that right.
                      Each variety has resistance to most major diseases.

                      However, if a variety is widely grown, the diseases are forced to adapt or die. So a slow mutation occurs in the local disease populations in order for the diseases to - each year - incrementally add to their arsenal of tricks to manage to get a foothold on the plant.
                      Eventually, one of the billions of fungal spores, which happens to have the right mutations, just happens to land on the right tree at the right time, and then multiplies. It soon spreads through the tree and to any varieties of the same type within wind-drift distance. Eventually, due to wind drift and after many years, the new strain of disease can spread across an entire country.

                      So when we say a variety is resistant or susceptible, it refers to the local diseases which have built-up over the many decades of that variety being grown.
                      So, for example, a hundred years ago, Bramley was resistant to all three major diseases: scab, canker and mildew.
                      After millions of Bramley trees have been attacked by diseases for over a century, there are now certain strains of disease which can cut through Bramley's disease resistance like a hot knife through butter.
                      However, those strains which can demolish a Bramley are usually so specialised that they are unable to attack the large majority of other varieties.
                      So if you take a scab isolate from Bramley and put it on (say) Worcester Pearmain, there's a good chance that the disease will not have a mechanism to get past Worcester's resistance.
                      However, Worcester has also been widely grown and there are specialised strains of scab which can demolish a Worcester tree. However, those strains of scab will have little impact on a Bramley.

                      So the trick to a healthy orchard is to grow only one or two trees of each type (just as a wild seedling forest of apples would be genetically different) and also to grow varieties which are less common, on the basis that there will be less strains of disease able to attack them (if at all) and it is likely to take the diseases a long time to find ways round the unusual variety's resistance.
                      It is virtually impossible for diseases to be good at attacking all varieties due to so many different mechanisms of resistance (imagine the diseases as criminals - having to carry a whole lorry load of tools and weapons if they want to be able to attack every variety - compared to a bank robber who just needs a shotgun and a getaway car); diseases nowadays tend to be masters of attacking one variety, using one or two specialised tricks to get past a variety's resistance, but not posessing the tools to commit other crimes).

                      However, "unusual" varieties which are related to common varieties (such as Cox offspring in the UK) will, of course, be more easily attacked due to inheriting half of Cox's resistance genes - all of which have been defeated by UK disease strains. So with Cox offspring, only the other parent's disease resistance will be present in the offspring in order to fight off Cox diseases. So Cox-offspring will have half the durability of resistance as compared to offspring from more unusual variteties.
                      Last edited by FB.; 09-06-2012, 08:43 AM.
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                      • #12
                        I am in the northwest (lancashire) and the varieties are james grieve and elstar (grafted onto one miniature tree).

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                        • #13
                          Originally posted by moonjooce View Post
                          I am in the northwest (lancashire) and the varieties are james grieve and elstar (grafted onto one miniature tree).

                          Lancashire tends to be wetter than average, so there will always be a lot of scab in your area, which will be capable of blowing on the wind from old/sickly/neglected trees up to several miles away.

                          James Grieve is widely grown in the North for its hardiness and reliability for cropping well in cold regions. However, due to being widely grown in that area for many decades, there are many diseases which are well-adapted to attack it. I lost my James Grieve just a few weeks ago, to one the most extensive and rapid canker attacks that I have ever seen/heard of (we've had a never-seen-before wet period in recent months).
                          It had been trouble-free up to that point.
                          Keepers nursery also speaks of James Grieve's tendency for disease:
                          James Grieve - Apple - Fruit Trees

                          Elstar is a modern variety which is widely grown in Europe. It was bred from the widely-grown Golden Delicious (whose resistance has been defeated due to being widely grown) and Elstar was selected primarily for its commercial use and therefore was not selected for any notable disease resistance, unlike many old (pre-1900) varieties which were raised in an era before sprays, where natural selection would get rid of those which were not fortunate enough to inherit much resistance from their parents.
                          Again, Keepers nursery confirm its lack of disease resistance:
                          Elstar - Apple - Fruit Trees

                          So you may be fighting an uphill battle to control diseases. However, I'd see how they go next year without spraying and then make a decision about what to do.
                          It would be easy enough to re-graft your established tree with a couple of varieties carefuly chosen for particularly strong resistance to disease, so I certainly wouldn't get rid of it.

                          I have a Bramley which is the woolly aphid's favourite. Every year it gets severely attacked - completely covered - and I mean completely - with white fluff. The woolly aphids are flying-in each year from several neglected old trees nearby, and also seem to have taken residence on hawthorn hedges of some nearby gardens.
                          Fed up with this constant battle against the woolly aphids, I have re-grafted the Bramley to a different variety. The trunk and short length of the original main branches are all that remain of the Bramley part.
                          .

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                          • #14
                            I grow Elstar (near York) and would not call it disease-prone. Neither it nor its relation Golden Delicious are widely grown in the north of the UK so if you are lucky the local disease population may not know what to do with it. It does seem to suffer from mildew though (usually a problem in dry periods). The main thing is it has a superb flavour when home-grown, so I would persevere.

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