Monstera Deliciosa help!

I’ve had my beloved monstera for about a year now, I raised him from a single cutting and now he’s grown 7 new leaves. I noticed mealybugs on him last week so I took him outside, hosed the bugs off and sprayed the leaves with soap & water to kill any remaining bugs. Now the leaves are turning black, even the brand new one that just opened last week. Google said the black spots were most likely root rot, so I took him out of his pot, sprayed all the soil off the roots but didn’t find any rot, in fact his roots look pretty healthy. I repotted him in a new pot with fresh soil but the black is spreading. What can I do to save him???

 

Hmmm, I am not sure. I know that a lot of people use soap and water, but I never have. I read an article once, I can't remember where now, that said that the average dish soap has over 70 compounds that can harm plant tissue. I think the Insecticidal Soaps are specially formulated for plant use so probably more pure. Did you leave the soap on the plant? Or rinse it off? If you left it on and the plant was in sunlight it may have caused burning. I know this won't be a popular statement for me to make, but...I have a 1740 sq ft greenhouse that is intensively planted with over 1000 plants of all genera, and I am also a licensed nursery, so I HAVE to have fast eradication of any pest outbreak that occurs to prevent its spread to other plants. So I use Orthene. I know, its an organophosphate and its toxic. But it really has been improved over the years, it comes in a granular form now instead of the liquid form, and it only takes 3/4 tsp to make an entire gallon of solution. And it works, without damaging any plants. I tried to be a good little organic gardner for a few years and used nothing but Neem Oil but it just did not do the job.

 

Couple articles with caveats on homemade soap solutions:

• Control Houseplant Insect Pests Safely With Insecticidal Soap
• ENY344/IN1248: Managing Plant Pests with Soaps

 

Those are excellent articles

 

Walrus, you can get the same result on the mealybugs by just repeating your blasting them off every time you water. I know it's a hassle to drag a big plant out & back, but you can have most all of them gone in a month, and a complete cure in just a few months without any poisons, chemicals, or soaps.

It seems like those leaves are perhaps a little big to not yet have their full split pattern, which may indicate your light is a little too low. Monstera is such an aggressive grower that you can easily outgrow this minor bacterial spotting by just giving them enough sun and water (with decent drainage). Does your pot have a drainage hole? Does it at least get some direct sunlight on the leaves every day? Once you get enough light, also make sure to fertilize them regularly, it makes a big difference.

 

Thank you so much, this is very helpful... I was ready today to cut some of the remaining leaves to try and propagate a new plant but my roommate talked me out of it, saying the plant had already experienced enough shock, being repotted & such when I was checking for root rot. He is in a pot with drainage holes, & has been in the same SW facing window (behind a sheer curtain) since the beginning. I’m not too worried about the lack of fenestrations, since I started the plant from a single cutting (I read it takes 4-5 leaves before you’ll start getting splits) but I will maybe move him up onto the table to get a bit more light. Thank you so much for this info, it’s encouraging; I’ll keep nursing him with sun/water/fertilizer for now and let him outgrow the bacteria.

 

I have never been able to eradicate mealybug on a plant by just washing them off with water. But that is just my experience

 

I have been spraying and dabbing alcohol on a plant with few enough leaves that I can examine every leaf and stem. I am sort-of winning, but that is only after I got rid of another two plants with too many leaves to inspect, one in a pot too heavy to keep taking to the bathtub. With the source plant gone, there are fewer outbreaks on the remaining plant they like, and I seem to have it under control, if not entirely eradicated.

 

This time of year, going into fall, I always seem to get outbreaks on my ALocasias and some of the Heliconias. I am extremely leery of alcohol. I am afraid it will burn my plants.

 

Bihai, it's different for you growing in dirt, and also with such a big greenhouse. It's obviously not practical for you to follow the advice to take every plant outside and carefully blast the bugs off. Instead, you would have been just blasting the bugs from one side of your greenhouse to the other. Water-only works excellent for houseplants and small greenhouses where you can actually remove the plants from their environment to spray them. In fact, a very sharp spray of water works better for mealybugs than most soaps, which often don't penetrate the nests well enough to be 100% effective. The best spray is from a cheap 7-way hose nozzle from any home center, set to the "flat" setting. The pic below is one of the counters to the side of my kitchen sink. Several years ago I was lazy and let a mealybug infestation run wild there. It took hauling them all out three times to completely cure them.

 

@Tom Hulse, post that photo just above in @bihai's WOW thread or somewhere, so I can ask the name - well, just post it with the name. I don't want to hijack walrusgumboot's thread.

 

Hello, wondering how your monstera is doing and if you ever found the root cause and the solution. Please let me know since it might help my monsters too. Thanks

 

Sadly I never did find the root cause; in addition to my monstera I had a majesty palm, a bird of paradise & a pothos that all succumbed to mealybugs :’( With all of the plants I found the bugs made their way into the stems, where I couldn’t reach them with alcohol or a water blast, & they ate my plants from the inside out. Just today (2 hours before your message actually) I finally gave up on my monstera after monitoring it & keeping it in the sunniest spot in the house for 2 months. I cut the healthiest looking leaves off at the nodes as a last ditch effort to propagate new plants.

 

Please don’t worry about hijiacking my thread, I will read all of the plant advice I can find! :)

 

I should add that, living in Toronto in January, hauling the plant outside for a blast multiple times sadly wasn’t an option for me, but @Tom Hulse ‘s advice is solid. You might find better success if you’re on the west coast or in a milder climate.

 

So sorry to hear about your plants and the Monstera. I am also becoming quite devastated not being able to find the root cause. I live in Vancouver and the temperature is usually above 6c but the mother plant is 7 years old and about 2 meters tall so I cannot really take it for a shower. But the good thing with Monstera is that you can easily propagate it. I now have 5 baby plants. So the mother Plant has lots of kids . I was going to ask for some more pictures of the leaves and the stem to see if I have the same problem that you do. I also posted some pics yesterday and today in case you want to see. Thanks