Aussies Living Simply

Potato Pests ID

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  • #251015
    DepomeDepome
    Member

    I’ve just returned from a week away, during which time Toowoomba has had constant rain/drizzle. It’s been mid-20s temp-wise. My quite guarded, north facing vege garden (half of which is potatoes) has sprung something fungal looking. I said powdery mildew at first, and quickly removed the affected leaves to buy me time while I do some research (no experience). But now that I’ve looked at images of very flat looking powdery mildew, I think I have something slightly different. This is very rounded, but I have no doubt is still a mould of some kind. Within twelve hours of removing the bad parts, there is quite a bit more further back. The ground seems to have a bit too, though I think it might be on the lucerne mulch rather than the soil itself.

    I was hoping to avoid buying copper or sulphur sprays (money tight this week) but I’ve read that milk spray and bicarbonate spray may not be that affective once it has really taken hold.

    What I’d really like to know is what it is, and how to treat it. Do I need to remove damaged leaves and stems? The seeds were from The Lost Seed incidentally, though I think this issue is climatic rather than seed quality. I only have this one little vege bed at the moment so I can’t simply grow potatoes in a more ventilated area. I have to say, I didn’t think I’d ever see so much consistent rain in Toowoomba again, so I’m pleased in one sense!

    #449481
    KasaliaKasalia
    Member

    It could be white mould which is caused by high water and lack of ventilation. Given that the bed it is in a cnr and lots of rain may be why. If it is this the soil can harbour the mould spores for future crops of various things eg tomatoes.

    I am not sure of how to kill it but I have heard for the soil to cover in black plastic and kill it off that way. It may be a start anyway for your research. I dont think natural fungicides is the way seeing that the problem eg. ventilation and constant dampness may be the cause.

    Good luck. I grow my potatoes in milk crates ( or try large pots) which may be a way for you to go as well in the future.

    #449482
    Lyn BagnallLyn Bagnall
    Member

    Depome, I think Kasalia is correct in both her diagnosis and advice. :tup:

    There are more details on this disease “white mold” which is more commonly known as Sclerotinia rot in Australia. See:

    http://www.potatodiseases.org/whitemold.html

    You have to remove and burn infected plants immediately. This disease is common in areas of high humidity where proper crop rotation is not practiced. You will have to avoid planting susceptible crops in that area for some years. Beetroot, spinach, sweet corn and onions are not affected by this disease. In the meantime, you will have to grow susceptible plants in large pots, foam boxes. Sorry, we can’t give more cheerful advice. ๐Ÿ™‚

    #449483
    DepomeDepome
    Member

    S’ok Lyn. We only planted it about two months ago as it had azaleas when we moved in back last August. I’ll have to look up susceptible crops of course, but I’m not too stressed at the mo ๐Ÿ™‚ Thanks for the tips.

    #449484
    DepomeDepome
    Member

    Can I just get some clarification…. do I only need to remove the parts infected (which are spreading daily anyway) or the entire plant that is affected? I would think that black plastic on the soil now will make the situation worse :confused: The rain seems to have stopped at last, so I expect it to become hot and dry again soon.

    #449485
    Lyn BagnallLyn Bagnall
    Member

    Depome, you need to remove all the plants and burn them or put them in a sealed garbage bag for transfer to the tip. The black plastic is spread over the whole bed and anchored to keep the whole bed completely dry. It will also absorb heat at this time of year. Heat and dryness will help to kill off the spores in the soil – otherwise you are going to have an ongoing problem with this bed. ๐Ÿ™‚

    #449486
    DepomeDepome
    Member

    Only just checked back, sorry. I’ve only removed the affected parts, and the plants are still doing REALLY well. There’s just the odd white piece of straw in the bed now. Do I really have to sacrifice all of the plants? :uhoh:

    #449487
    dustygrl70dustygrl70
    Member

    How old are the plants Deborah – have they set a crop yet? If not maybe just cut your losses and pull them.

    We worked around sclerotinia in cropping for many years and sometimes it can simply reduce yield rather than take out a whole plant. If you get more prolonged wet weather this season it would most likely take over and the potato stems will rot through = dead plants. But if it stays dryish and you are carefully hand watering, the disease may hang around but not progress too much. And you may get a potato crop.

    surface mulch favours sclerotinia forming on growing stems that are touching the mulch, so if you can lift them clear of the mulch that helps.

    I understood that cereals/grasses were not susceptible, so perhaps a quick green manure crop of a cereal might help after the potatoes come out – we used to grow millet as our green manure and it significantly reduced disease levels in the subsequent crop.

    #449488
    DepomeDepome
    Member

    The plants are thriving, but I have no idea what’s going on beneath the surface as I haven’t tried to bandicoot. I’ve removed about three stems, but we still have plenty of new ones growing through the soil. I planted them about two months ago and apart from a few pieces of white straw (small pieces) you wouldn’t know there are/were any issues at all. Toowoomba is incredibly dry generally, as you will know, so while it is the ‘wet’ season (for want of a better description) it is unlikely that we will get another week of rain. The garden beds have thoroughly dried out now. I think that removing the white bits of straw to steady the dispersion of spores is probably the most productive thing that I can do. The plants look fabulous so it seems daft to dig them up :noapprove: but then, I’m no expert :confused:

    #449489
    Lyn BagnallLyn Bagnall
    Member

    Depome wrote:

    The plants look fabulous so it seems daft to dig them up :noapprove: but then, I’m no expert :confused:

    If the plants looks healthy Depome, just observe for the time being and only remove them if they start looking sick รขโ‚ฌโ€œ but avoid planting any other members of that family in the bed for 4 years. ๐Ÿ™‚

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