I just joined the forum today and wanted to see if anybody can help.
I'm growing 18 gorgeous Japanese cucumber plants. I was able to grow a couple of plants last year before they suffered from bacterial wilt. I've got traps out for Japanese beetles and have caught hundreds of them. The plants are resistant to downy mildew and powder mildew.
Three days ago I noticed small white spots on my oldest and largest plants. The white spot gets dry and cracks and spreads across the leaf and then the plant. Thus far it hasn't affected the harvest nor has it completely killed the affected leaf but I would like to take preventive action. I don't think it is powdery mildew. There is nothing on the underside. I haven't seen any aphids but I have seen some tiny bright green bugs that jump away when I get near them. I cut a few affected leaves the first day but I'm afraid to cut anymore as whatever I have going on is spreading. Is this something I should be worried about? Any idea what it could be? I have some insecticidal soap but prefer not to treat anything chemically. I have tons of beautiful bees in my yard and want to keep them!
I have lots of cucurbits...Kabocha pumpkins, Japanese watermelon and sugar pie pumpkins. If I have a problem in the cucumbers it could turn into a larger problem.
Thanks for any suggestions!
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Dragonmom
- Newly Registered
- Posts: 4
- Joined: Mon Jul 18, 2011 2:44 pm
- Location: Suburban Charlotte, NC
I think I've identified my problem and thought I would post it here in case anybody else has a similar problem. I've eliminated about everything else so I think they are spider mites. I did see some very tiny little spiders, though I always thought spider mites are too small to see. They might be big from feeding on my beautiful cucumber plants. I'm going to spray insecticidal soap tonight and hope it is dry by the time the bees get up in the morning.
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jal_ut
- Super Green Thumb
- Posts: 7447
- Joined: Sun Jan 18, 2009 10:20 pm
- Location: Northern Utah Zone 5
Welcome to the forum.
I don't know what is causing your problem. Hope you have identified the culprit. The thing about soap is that it will only affect the bugs you actually spray it on. It has no residual consequences. It can sometimes burn the leaves of plants. I would try it on a leaf or two first to see if the leaves will be damaged. Also, soap acts immediately and within a minute you can rinse it off the leaves with fresh water. What bugs you hit will already be goners.
There has been some good discussions on soap on this forum. Use the search function.
I don't know what is causing your problem. Hope you have identified the culprit. The thing about soap is that it will only affect the bugs you actually spray it on. It has no residual consequences. It can sometimes burn the leaves of plants. I would try it on a leaf or two first to see if the leaves will be damaged. Also, soap acts immediately and within a minute you can rinse it off the leaves with fresh water. What bugs you hit will already be goners.
There has been some good discussions on soap on this forum. Use the search function.
You can see spider mites. I have had somewhat extensive experience with them when I brought my dwarf meyer lemon indoors into a 'greenhouse' room I created in a storage room in my house. I kept humidity around 75% and heat around 80F. While I was able to rejuvenate my meyer lemon from sticks to a flourishing plant, I brought spider mites by the 1000's into the room.
There are two main types, and I won't get scientific about this to make it simple. There are reddish ones and there are semi opaque ones with a couple black spots on their back. A handheld 5x magnifying glass is enough to determine which.
You can also mist your plants with a sprayer and you'll see the webs at the interface of the leaves and branch as well as branch splits. You'll only see this if they have multiplied into somewhat significant numbers.
Spider mite eggs look like tiny pearls on the underside of the leaves. They don't lay them in any order like a ladybug might. The kinda look like the pearls that develop on young okra plants, but are significantly smaller.
The mites I had spread from the lemon tree to basil and quite a few other plants in my greenhouse. I ended up buying predatory mites that eat them. While the predatory mites will decimate a spider mite infestation, it takes too long for the predator mites to multiply into the numbers you need before a small amount of plants is overrun and destroyed by the pest mites.
The best way, I found, to get rid of them is to spray the leaves with a stiff mist and then just wipe them off. Or check each leaf and smash them. As Jal said, sprays risk the health of the plant. IF you get a decent compressed air water spray bottle, you can adjust the spray to simply spray them off. You'll have to pay attention to get them all off, though. But if you repeat this process over a couple days, hitting what you can day by day, you'll get the infestation under control.
The last problem you face is identifying how far they have spread. Spider mites, in my experience, don't really discriminate. They'll spread to anything they can reach - touching plants almost always get mite transfer. My infestation started on my meyer lemon. I paid most attention to it while not paying attention to the basil next to it. Once I had the meyer infestation under control, I noticed them on the basil...and then on the dill, and then the flowers we were growing...and they had even crossed the pot to the humidifier and were crawling all over it. They like the humidity. The more humid, the more they thrive when the temps are right.
As for predatory mites, you have to introduce them early if you want them to handle your problem or they will not replicate quick enough to get ahead of the pest mites - as I said. While they reproduce twice as fast as the pest mites, they can't catch up with a massive infestation. However, if you can get the predatory mites in early, they'll handle the problem in short order. Predatory mites don't eat plants, only mites. Once they kill all the available pest mites, they will start eating themselves until they are all gone/dead.
There are two main types, and I won't get scientific about this to make it simple. There are reddish ones and there are semi opaque ones with a couple black spots on their back. A handheld 5x magnifying glass is enough to determine which.
You can also mist your plants with a sprayer and you'll see the webs at the interface of the leaves and branch as well as branch splits. You'll only see this if they have multiplied into somewhat significant numbers.
Spider mite eggs look like tiny pearls on the underside of the leaves. They don't lay them in any order like a ladybug might. The kinda look like the pearls that develop on young okra plants, but are significantly smaller.
The mites I had spread from the lemon tree to basil and quite a few other plants in my greenhouse. I ended up buying predatory mites that eat them. While the predatory mites will decimate a spider mite infestation, it takes too long for the predator mites to multiply into the numbers you need before a small amount of plants is overrun and destroyed by the pest mites.
The best way, I found, to get rid of them is to spray the leaves with a stiff mist and then just wipe them off. Or check each leaf and smash them. As Jal said, sprays risk the health of the plant. IF you get a decent compressed air water spray bottle, you can adjust the spray to simply spray them off. You'll have to pay attention to get them all off, though. But if you repeat this process over a couple days, hitting what you can day by day, you'll get the infestation under control.
The last problem you face is identifying how far they have spread. Spider mites, in my experience, don't really discriminate. They'll spread to anything they can reach - touching plants almost always get mite transfer. My infestation started on my meyer lemon. I paid most attention to it while not paying attention to the basil next to it. Once I had the meyer infestation under control, I noticed them on the basil...and then on the dill, and then the flowers we were growing...and they had even crossed the pot to the humidifier and were crawling all over it. They like the humidity. The more humid, the more they thrive when the temps are right.
As for predatory mites, you have to introduce them early if you want them to handle your problem or they will not replicate quick enough to get ahead of the pest mites - as I said. While they reproduce twice as fast as the pest mites, they can't catch up with a massive infestation. However, if you can get the predatory mites in early, they'll handle the problem in short order. Predatory mites don't eat plants, only mites. Once they kill all the available pest mites, they will start eating themselves until they are all gone/dead.