Blackberry leaves infected with Septoria leafspot. Scan: Lisa Johnson, LSU AgCenter.
Ruby from DeRidder brought a sample of blackberry leaves infected with leafspots and wanted to what was causing this problem and how to treat it. Also, she wanted to know if it is spreading.
These leafspots look like they are caused by Septoria fungal spores. Dan Gill discussed treatment of Septoria in 2015, “Remove diseased leaves. If caught early, the lower infected leaves can be removed, bagged, and disposed of. However, removing leaves above where fruit has formed will weaken the plant and expose fruit to sunscald. Do not compost diseased plants.
Improve air circulation around the plants. Make sure plants are spaced properly.
Mulch around the base of the plants. Mulching will reduce splashing soil, which may contain fungal spores associated with debris. Apply mulch after the soil has warmed.
Do not use overhead watering. Overhead watering facilitates infection and spreads the disease. Use a soaker hose at the base of the plant to keep the foliage dry. Water early in the day.
Use crop rotation. Next year do not plant tomatoes back in the same location where diseased tomatoes grew. Wait 1–2 years before replanting tomatoes in these areas.
Use fungicidal sprays. Fungicides will not cure infected leaves, but they will protect new leaves from becoming infected. Apply at 7 to 10-day intervals throughout the season. Apply chlorothalonil, maneb, macozeb, or a copper-based fungicide, such as copper hydroxide, copper sulfate, or copper oxychloride sulfate. Follow harvest restrictions listed on the pesticide label.”
The disposal of infected leaves and stems will prevent the spread of this disease by fungal spores from these old plant parts.
Wilted hydrangea possibly caused by a soil borne pathogen. Photo: Cathy Farris, Master Gardener.
Cathy of Oakdale sent an email with a question and a picture, “…A friend asked me what was happening to her hydrangeas??? They were in shaded moist soil. Do you have an idea?”
Figure 2. Wilted hydrangea possibly caused by a soil borne pathogen. Photo: Cathy Farris, Master Gardener.
There are two possible causes for the wilting of this hydrangea: bacterial wilt or Armillaria root rot. A conclusive diagnostic test to the AgCenter’s Plant Diagnostic Center would cost $25.
Plant pathologists from Tennessee State University made these recommendations, “Eradicate the infected plant parts can help to reduce bacterial leaf spot and bacterial wilt diseases…There is no chemical control available for bacterial wilt disease.”
UConn Home & Garden Education Center recommends these practices for wilting hydrangeas, “Good growing conditions are the best defense against Armillaria root rot. Water during summer droughts and fertilize according to soil test results. There is no chemical control…Do not plant hydrangea where flooding occurs after a heavy rain.”
Grounsel bush or eastern baccharis. Photo: Jimmy Earl Cooley, Master Gardener.
Jimmy sent in a couple of images of a bush and wanted to know its name.
The Missouri Botanical Garden (MBG) supplied this narrative on its website, “Baccharis halimifolia, commonly called eastern baccharis, salt bush, or groundsel bush, is a fast-growing, medium to large, deciduous shrub native to the Atlantic and Gulf coastal plains of the eastern and southern United States. It typically grows in exposed, sandy areas, salt marshes, roadsides, ditches, and other open, disturbed sites.”
The MBG also included these ecological benefits when describing eastern baccharis, “The flowers are attractive to bees, butterflies, and other insect pollinators. The densely branched habit of this plant provides nesting habitat and cover for birds and other animals.”
Woolly oak galls. Photo: Ben Gutierrez, ask.extension.org.
Bill observed a kind of deformity on his oak leaves and inquired, “I was noticing numerous unknown growths on fallen leaves. The do not move or have any noticeable characteristics that would identify them as insects. When I tear them apart, there does not seem to be anything except what might be described as a ‘fur - like ball.’”
Last year in 2019, Dan Gill, retired AgCenter horticulturist, had a similar question and replied in his Get It Growing column, “It is an insect infestation called wooly oak gall. The tiny insects infest some of the oak leaves in the spring and cause the leaves to grow the fuzzy tan galls on their undersides. The insects live and feed inside the galls during the summer. The damage is negligible, and the insects have come and gone at this point. Live oaks tend to drop leaves with galls in the fall, which provides us with great leaves for mulching a composting. Leaf drop may also occur around February, the time when live oaks typically shed leaves. So, bottom line, there is no harm caused by wooly oak gall, you do not need to be at all concerned and there is no need for any treatments.”
If you want to contact Roots, Shoots, Fruits and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 337-463-7006 or firstname.lastname@example.org. Also, you can be on the “green thumbs” email list by emailing your request to the address above.
“Before you buy or use an insecticide product, first read the label, and strictly follow label recommendations. Mention of trade names or commercial products in this article is for informational purposes only and does not constitute endorsement by Louisiana State University AgCenter.”
“This work has been supported, in part, by the USDA National Institute of Food and Agriculture, Renewable Resources Extension Act Award, Accession Number 1011417.”