Q.Houseplant Pest Dilemma
At my office we just purchased four new plants that I have been responsible for. We have a large corn plant, a large croton, a date palm, and a Thai plant. We have had them about 3-4 months and they all just came down with pests. The palm appears to have mealybugs from what I have found online, the croton has spider mites, corn plant has spider mites and the Thai plant appears normal. This literally happened over the weekend. I inspect and watered them on Friday and they are infested on Monday. I need to eradicate the pests immediately and quickly. I don’t have time to sit and pick off the mealybugs one by one. I don’t care what it takes or else the plants are going in the trash. HELP!!!
I've been a professional interior landscaper for 30 years, and I'll give you the recipe that I used for most of that time to control bugs. 1 teaspoon of soap (mild liquid dish soap, or liquid castile soap from the health food store) in 2 cups of water, add about 1/4 teaspoon of vegetable based oil like canola or corn or coconut. Spray this all over the plant till it drips. Spray especially up onto the bottoms of the leaves, and down into the leaf axils (where leaf stem joins main stem) and along all the stems. The first time you do this, wipe the leaf surfaces, top and bottom, thoroughly with paper towels. Then spray again. What's happening is that first you wipe off as many of the bugs as you can, then spray what's left. The soap interferes with the breathing processes of the bugs, whether spiders or mealies, and they die, but only the ones that the soap falls on. Therefore, you need to spray weekly for 4 weeks. This way you kill the new bugs as they hatch, before they can lay more eggs.
To tell you a little more - your plants had bugs long before last weekend. You just didn't see them. It takes a lot of experience to see them at the beginning stages.
I applaud your interest in putting some plants into your office environment. The trouble is, there's a lot more to it than just buying some plants, plunking them down, and watering them once a week. The plants shouldn't be infested with bugs if they're in good health. Also, while the corn plant is a good subject for beginners as it is a highly adaptable plant, the other three are quite a bit more difficult. Crotons almost always come down with spider mites, so they need to be misted weekly to show up the earliest signs of webbing. Most Hawaiian ti plants (cordyline species) don't make very good indoor plants at all, and date palm - I'm assuming you mean pygmy date palm, phoenix roebellini - don't work well unless they have very high light. Some easier plants of similar appearance would be neanthe bella or areca palms; aglaonema with their bright leaf variegation; large-leaf philodendron such as "painted lady," with their mahogany-tinged leaves; peace lily, with lovely white blooms.
You might try calling a plant care company in your area. You might find one that will help you out, or you might find that the cost of having professional care (which comes with guaranteed replacement of plants that don't do well) might be within your office budget.
Hee's an article with some more information: https://www.gardeningknowhow.com/houseplants/hpgen/best-office-plants-good-plants-for-the-office-environment.htm