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I bought 2 mini kiwi plants (Actinidia arguta Issai) online. It was delivered from Netherlands in case that matters. They are growing well except for black spots that seem to be spreading a little lately.

It doesn't really look like fungus and I can't find any other mention of this type of symptom. It has been unusually dry and warm for the last few weeks here in Ireland so fungus seem particularly unlikely. Unlike fungus the black areas aren't really spots but rather small section of the leave between small veins. It affect mostly smaller but not the smallest leaves.

One plant is still in a pot and one is in the ground with different soils and even uncomposted waste buried beneath. They both have the same issue. I see no pests except for a few small shield bugs or at least something that looks like it. Could shields bugs cause this? What else could it be?

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DominicM
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The first picture is showing black aphids. I think if I am seeing this picture clearly. Fungus are the black spots that your plant actually is cutting off from its vascular system, allowing that area with the fungus to die, blacken and get crispy then fall out of the hole. Called Shot hole.

Plants take care of themselves as long as they are healthy. As long as they are getting what they need; proper amount of light, ventilation, water (not too much not too little), great drainage and the correct amount of chemistry so the plant can make its own food via photosynthesis. That is fertilizer. Fertilizer is not plant food nor is it 'nutrients'...it is simple chemistry plants have to have to grow within our artificial gardens with our artificial needs.

Cut off the leaves with aphids. Squish the aphids with your fingers. A hard spray of water works okay. Soapy water spray works okay. Neem sprayed at night would be best. Your Kiwis will take awhile to mature and be able to produce Kiwis. Neem will not be transferred to your edible fruit now. You need to take care of the insect problem now,spray at night once and if you see more aphids, then perhaps one more spray session. Lay your potted plant on its side to spray, get beneath the leaves. The planted Kiwi, just try to spray beneath the leaves.

The dark spots will always come and go. That is the plant taking care of itself. Not a big deal at all. Your Kiwi's look a bit anemic. Have you ever given them fertilizer? Healthy plants protect themselves from disease and insects. Plants without proper chemistry for health will be susceptible to insects, disease, fungi....did you happen to purchase a female and a male Kiwi? I have never heard of a MINI Kiwi. These are vines, tough and very hardy vines once they are established. A female and a male to pollinate the female are a must.They don't even have to be the same species.

I haven't looked up the name you listed for these Kiwis. I will look them up and be back if there is anything novel about your species of Kiwis.

hardy Kiwi care

stormy
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  • The Issai variety is self pollinating. There are no aphids on the leaf. The black parts are just dead parts of the leaf. Black sections are the very small parts between veins that are dry and dead, kind of irregular diamond shape. Aphids aren't really a problem outdoors here, as there is usually constant rain and wind. – DominicM Jul 04 '18 at 08:02
  • I am sorry, it is tough to 'see' stuff in photos very well. Did you say what it is you've done for fertilizer? I looked up Issai variety but didn't hang out long enough to learn it was...self pollinating. What does 'mini' kiwi mean? – stormy Jul 04 '18 at 10:21
  • Mini kiwi is just a common name for the fruit/plant, specific variety is Issai. Haven't fertilized it much as the compost is very rich and the plants are still fairly small. I might have added a little general purpose non-organic fertilizer as well. Apart from shieldbugs I've also noticed a few small red spiders on the plant. They are much larger than spider mites though, not sure if they could be the cause. – DominicM Jul 05 '18 at 11:15
  • Spiders are always the good guys. Spider mites are related to spiders and actually suck their meals from plants so not at all good. The black then, would be honeydew. Some insects whether aphid or whatever poop and piss on the leaf and then bacteria come in to eat that poop and piss and the bacteria cause the black stuff. https://en.wikipedia.org/wiki/Honeydew_(secretion) I am glad you used a balanced all purpose fertilizer. Compost is not 'rich', it is either raw or it is decomposed. Great stuff but not fertilizer. – stormy Aug 05 '18 at 20:52
  • What type of soil is in the pot? Which plant are we looking at in the picture? The potted one or the one planted in the garden? Shield bugs or stinky bugs aren't a problem unless they come as a crowd to a limited buffet. They actually eat aphids and whitefly..I would plant the other kiwi in the ground as well. Keep the roots cool and don't plant the other kiwi unless it is used to the out of doors sunlight. You'll need to acclimate it if not. You had some sort of aphid that got eaten up but left its sugary pee behind to be used up by the bacteria and fungus that makes the black. – stormy Aug 05 '18 at 20:59
  • This is the plant in the ground but the potted one has same symptoms. I don't see how this could be aphids. There are no signs of aphids or mites. The black parts are dead/dry parts of the leaf, not any sort of a film. – DominicM Aug 06 '18 at 21:12
  • @DominicM I agree, the black spots are dead plant tissue and/or blackened honeydew. The aphids or what ever insect are gone. There might be at least 2 or 3 different reasons one for each blackened spot on a leaf. Remember I am looking at a picture or two. I see what I am used to seeing. I see honey dew. That means there used to be insects, sucking insects that as they suck up the carbohydrates in the xylem and phloem they were pissing/pooping it out at the same time onto the leaf. Then bacteria and fungus use that sweet sticky honey dew for 'food' and it turns black. – stormy Aug 06 '18 at 21:19
  • It's not honeydew, there is no materiel on the leaf at all, just dead/dry sections of the leaf. No bug were ever visible and I did check periodically. I would guess it's fungus of some sort. The plant in the soil seems to be overcoming it. – DominicM Aug 07 '18 at 22:25
  • Well, I am glad that it isn't honeydew. And I am hearing that you are aware of your plants and are seeing them. Then the black would be fungus (honeydew is as well)...as long as there seems to be nothing that is promoting this fungus your plant should do well. And you are definitely a gardener in the making! – stormy Aug 07 '18 at 22:33