We viewed the photos. The roots look good (firm and white) and the crown looks ok. We notice some slug damage (holes) in the foliage and the brown spots looks like anthracnose, a fungal disease. Infection can occur if leaves are wet for prolonged periods. If you have to water, do so early in the morning so leaves can dry by night.  https://extension.umd.edu/resource/anthracnose-disease-flowers

Also, it is possible conditions may have changed in the area such as more dampness, drainage patterns, etc. Check the drainage in the area and make sure the soil drains well. 

Hostas perform best in a moist, well draining soil in full or partial shade. They prefer high-filtered shade with one-quarter to one-half of the day in morning sun. You may want to thin the plants if not done recently to provide good air circulation.  Groom the plants removing brown, dead foliage and throw in the trash. Make sure mulch is thin and away from the base of the plants. No chemical control is recommended. 

Here is more on slugs and management techniques. They can be troublesome on hosta https://extension.umd.edu/resource/slugs-and-snails-flowers

Marian

You are welcome.

Marian

Dear Mary,

Thank you for using Ask Extension. A request for support has been created and a representative will follow-up with you as soon as possible. Questions are usually answered within two business days. You can view this question's progress online.

YOUR QUESTION #0037393:

Hosta issue

I have well-established Hosta that are showing sings of distress. Their leaves are yellowing (this is August 15th), and their root systems are thin. I have about 40 plants and most are showing signs of disease. Additionally, some of their stalks are wilting with seemingly rotting interiors. What’s should I do?

Ask Extension offers one-to-one expert answers from Cooperative Extension/University staff and volunteers within participating Land-Grant institutions across the United States.

If you wish to provide additional comments or information regarding the issue, please reply to this email or login to your account for a complete archive of your prior questions and answers.

---

This message for informational purposes only. It is not intended to be a substitute for personalized professional advice. For specific local information, contact your local county Cooperative Extension office or other qualified professionals. eXtension Foundation does not recommend or endorse any specific tests, professional services, products, procedures, opinions, or other information that may be mentioned. Reliance on any information provided by eXtension Foundation, employees, suppliers, member universities, or other third parties through eXtension is solely at the user's own risk. All eXtension content and communication is subject to the Terms of Use which may be revised at any time.

Dear Mary,

Thank you for using Ask Extension. A request for support has been created and a representative will follow-up with you as soon as possible. Questions are usually answered within two business days. You can view this question's progress online.

YOUR QUESTION #0037393:

Hosta issue

I have well-established Hosta that are showing sings of distress. Their leaves are yellowing (this is August 15th), and their root systems are thin. I have about 40 plants and most are showing signs of disease. Additionally, some of their stalks are wilting with seemingly rotting interiors. What’s should I do?

Ask Extension offers one-to-one expert answers from Cooperative Extension/University staff and volunteers within participating Land-Grant institutions across the United States.

If you wish to provide additional comments or information regarding the issue, please reply to this email or login to your account for a complete archive of your prior questions and answers.

---

This message for informational purposes only. It is not intended to be a substitute for personalized professional advice. For specific local information, contact your local county Cooperative Extension office or other qualified professionals. eXtension Foundation does not recommend or endorse any specific tests, professional services, products, procedures, opinions, or other information that may be mentioned. Reliance on any information provided by eXtension Foundation, employees, suppliers, member universities, or other third parties through eXtension is solely at the user's own risk. All eXtension content and communication is subject to the Terms of Use which may be revised at any time.

We will wait for your photos of the pieris japonica. Send photos of the whole shrub, around the base, and affected foliage so we can see what you are dealing with. 

Let us know how old the shrubs are, site conditions - sun versus shade, soil conditions, and how you care for the plants. 

It is possible you may be dealing with lace bugs. They are a sucking insect and  feeding damage first appears as white stippling or tiny white spots. These spots later merge and leaves turn yellow and severe infestations may cause premature leaf drop. Look under the foliage for black fecal matter (black dots). Stressed broadleaved evergreen shrubs grown in full sun suffer the most damage from the insect.

https://extension.umd.edu/resource/lace-bugs-trees-and-shrubs

Marian

Hello Mary,

Thank you for the photos. Unfortunately, they are fairly small and we are unable to magnify any to see clearer detail. From what we can see, the yellowing appears to be limited to just the older, more inner growth which would be consistent with normal autumn leaf shed. Evergreens do shed foliage, and often in autumn, just to a much lesser degree than deciduous plants. If this is occurring to a greater extent than in previous years, it could be due to chronic and perhaps cumulative stress the plants were experiencing this past summer and/or in recent years.

Lace bugs are still a possibility, though if present their damage doesn't look prominent. It's possible the Pieris were merely drought-stressed first, especially if they aren't periodically irrigated (as needed), which led to a minor lace bug outbreak or just the premature aging of the older growth, which is why it's yellowing and shedding this season. The shrubs' location next to pavement may be exacerbating any drought or heat stress they experience during summer; certainly, such conditions have been more taxing for landscape plants in recent years versus when the plants were younger.

We don't see clear examples of any darker leaves...are they somewhat blackened on their upper surface? If so, this sounds like sooty mold, a fairly harmless fungus (it doesn't infect plants) that grows on honeydew. Honeydew is a sugary residue excreted by sap-sucking insects such as aphids, scale, and spotted lanternfly. If the Pieris are pest-free, perhaps one of the trees above has a pest infestation that is raining honeydew down upon them. If so, no action needs to be taken and the sooty mold will weather off in time. You can inspect the Pieris stems and leaf undersides for scale, though they are not commonly infested by them; they will be small, glued to the foliage or bark, and generally white, grey, or brown: https://extension.umd.edu/resource/soft-scales-trees-and-shrubs

There is nothing you need to do now except to continue to monitor the plants for watering needs if they are in locations you are able to irrigate. Feel the soil about six inches deep in the root zone and water thoroughly when the soil feels fairly dry at that depth. This wooded habitat is definitely what they prefer, so should help minimize any environmental stresses going forward.

Miri