The bad news: I see this often. It is common on plants that have just arrived from Florida, where the growing conditions are good and a wide variety of chemical controls are used. We have asked the growers what causes this, but their answers were unhelpful.

The worse news: There are at least 23 species of Fusarium that affect Sansevieria. There are two common ones, but this does not look like them to me. Those two usually appear in the middle of the leaf or at the soil line and have a watery look. There are no good chemical treatments that I know of available to the home gardener for Fusarium in California.

There are also Colletotrichum sansevieriae and Chaetomella leaf spots.

Culurally, giving the plants warm sunny conditions, and keeping the leaves dry are obvious first measures. I have trimmed the blighted areas with a sterile razor blade, but one has to sterilize between every cut, which is tedious. After trimming more areas may appear.

It would be great to hear if anyone knows of an effective chemical control.

No one can really suggest a chemical treatment without knowing for certain what is causing the lesions. Plant diseases can only respond to a very narrow range of species specific chemicals. Your images aren’t really of much help in disease ID. Regardless, as has been said, many chemicals are restricted and unable to be used by non-professionals.

rockdale, did you contact the provider when you first noticed the problem?

If you live in the US, you can avail yourself of a local County Extension Service. There are branches in each county but they differ widely as to how useful they are and the services they offer. Some a fantastic, others, not so much.

The better ones can help you take tissue samples of your plants, pack them up and send them off to the Plant Pest Diagnostics Clinic at your state’s ag research university. The cost might be prohibitive for a couple of houseplants, I don’t know. Totally worth a phone call.

I stress the need to find out what the heck it is is because if a systemic disease, you won’t want to even take cuttings to start new plants. Wouldn’t it be great if the problem is purely cultural?

iochroma: thanks for the detailed information.I will research these things you wrote in your post.

rhizo_1: these plants are not newly acquired. I have grown them for several years lauren 5 years and bentels sensation at least 8 years. i was hoping it is a culture issue but seems both of you think it is some disease? i did neglect them mostly in winter and then we have more rains then usual this summer.

btw seems my zone (RI Z6) is not showing again beside my user name ?

I agree with Dori with regard to your plant. If we put The Principle of Parsimony/ Occam's Razor to work, it would suggest the most logical place to look would be a root problem involving over-watering or a high level of dissolved solids (salts) in the grow medium/ soil solution, both/either of which would account for the symptoms. Also, fluoride is accumulative in leaf tissues - it never goes away, and your plants are known to be sensitive to compounds containing fluoride. If your efforts at working to ensure these areas are NOT the issue, you might then consider whether or not the plant is worth the effort and perhaps start anew armed with some additional knowledge.

It's always good to understand that most diseases and even insect infestations occur because the plant is weakened by stress factors that involve the grower asking the plant to deal with cultural issues the plant isn't programmed to tolerate, and a very high percentage of issues are caused by unhealthy roots.

A healthy root system is an absolute prerequisite to a healthy plant, and you simply cannot have the later w/o the former. You should be able to water a planting such that the entire soil column is saturated and at least 20% of the total volume of water applied exits the drain hole and has no pathway by which to make its way back into the soil; this, without having to worry that your soil will remain waterlogged so long that excess water in the soil will deprive the root system of oxygen, and in doing so limit normal root function and/or negatively impact root health. Water uptake (and therefore nutrient uptake) is an energy-driven process that must take place in the presence of oxygen, an element/ nutrient essential to the 'burning' of the plant's food (sugar/ glucose) that produces energy for roots' metabolic functions. If your soil is too water-retentive to water in this fashion w/o the plant(s) having to pay a saturation tax, you might want to consider a more forgiving soil, or learn some new tricks that limit how much water a water-retentive soil can hold. CAN hold is different than WILL hold. Ideally, you would be using a grow medium that passively allows enough water to drain from soils that you needn't worry about root function/health issues. If it doesn't happen passively, you should take the active role to MAKE it happen; or, be willing to accept the limitations and issues that accompany soggy soils.

If the issue is an accumulation of fluoride, you can't fix the damaged leaves, but you can prevent fluoride issues involving leaves yet to form by watering with some form of water that doesn't contain fluoride. That could be distilled water, rain water, snow melt, air conditioner/ dehumidifier condensate, or water that has been filtered through a reverse osmosis system.

Questions or additional input?

Al

thanks tapla. They are in gritty mix. I don’t believe root is the cause - checked and also repoted. never considered fluoride can be an issue - have been watering with tap waters except when it rains. that could be it or some diseases.

Rockdale, Those plants you mentioned do have a problem with leaf rot. I do get that myself and I use a common over the counter mix used for Rose bushes called Ortho MAX Garden Disease Control Concentrate. Last a very long time (years). Every so often maybe twice a year I spray them down. Another thing I used to do and helps is to spray down plants with Mouth Wash. The active ingredient in original Listerine is thymol. New Listerine is alcohol free and alcohol is needed to kill germs and disinfect cuts and injures on leaves. I use the Dollar Store discount mouthwash with good results. Not to do this too often which would end up killing the plant .

Thanks Stush. I will give listerine a try. Glad to see you are still here. Have not log back in gardenweb as often as I would like. always think about my garden friends when I tend the plants sent from you. How have you been? Havn’t talk to you for a long time. Hope you and your plant had a great summer.

Are you able to add a closer pic of the questionable spots? I've had various rusts on a variety of plants over the years and they all make your hands orange if you touch them. Is that happening?