Why Did My Leaves Turn Black?

February 16th, 2023 by earthworksjax Lawn Care

Why Did My Leaves Turn Black?

Insect secretions of honeydew and the resulting sooty mold biofilm buildup are why your plant’s leaves turn black. The sooty mold has a mutualist relationship with sap-sucking insect pests that create favorable growth conditions for the fungus. Blocking photosynthesis is the only harm to the plant caused beside the unsightly appearance of this fungus. “On pecan (Carva illinoensis) these molds can reduce light penetration and photosynthesis by factors of from 25% to 98%,” according to Science Direct. “In addition, the darkening of the leaf surface can result in an increase in leaf temperature of 4°C.”

Plants whose leaves turn black include azaleas, camellias, citrus trees, crepe myrtles, gardenias, elms, hollies, maples, podocarpus, and mostly evergreen plants. Susceptible plants tend to have rigid leaves that hold up well to prolong infestations.

Aphids, scale, mealybugs, mites, scale, and whiteflies pierce and suck out nutrients from the host plant. They then secrete the sticky honeydew waste product that fungal spores attach to as the leaves turn black. While other plants, such as herbaceous perennials, can be affected by the same insects, they are more likely to die before the buildup of secondary black sooty mold.

There are two identified forms of sooty mold categorized as deciduous and permanent. “The deciduous growth form is characterized by a thin hyphal layer that peels away from its substratum in drier, cooler months,” according to Science Direct. “It is found predominantly in lowland tropical regions but is absent from rainforests. The deciduous form also occurs along the coast of the southeastern United States and commonly is found on citrus trees.”

While the type of sooty mold commonly encountered can dry up and flake off during cool and dry seasons, it’s most effectively removed by washing with soap and water. Soaking the leaves and hand washing will loosen the mold away. This can be also be done with insecticidal soap or horticultural oil that also treats the primary pests. However, horticultural oils should not be used during freezing or over 90F temperatures or drought-stressed plants. You might see mention of ‘dormant oils’, which are horticultural oils used to treat overwintering aphids, mites, scale, and other sap suckers’ eggs. Always read label directions making sure that the treatment suits your specific plant. And don’t use horticultural oil on azaleas, begonias, or succulents.

There is ongoing research into biocontrols of sooty citrus mold and the associated insects. Bacillus velezensis MT9 and Pseudomonas chlororaphis MT5. “These bacteria were shown to produce antibacterial and antifungal activities in the form of water-soluble molecules and were effective in vitro in inhibiting the growth of two fungal strains, Penicillium sp. YM1 and YM2, isolated from citrus soot,” according to researchers at the University of Salento, Via Monteroni in Italy. “Altogether these in vitro findings and pilot experiments with a limited set of plants indicate that Bacillus velezensis MT9 and Pseudomonas chlororaphis MT5 can effectively combat sooty mold possibly by acting on both the insects and the fungi that inhabit the black biofilm, paving the way for an innovative and sustainable tool to fight this disease.”

Beneficial insects such as Ladybugs, Lacewings, and some predator wasps are a long-term natural remedy for sap-sucking insects. However, maintaining a sufficient population can take time and effort. If you want to introduce them in your yard, consider available species from Arbico organics. Earth Works garden center has the organic treatments mentioned in this article available for purchase.

Earth Works Lawn Care provides Integrated Pest Management treatment programs based on what we see with pest populations throughout the community and your specific landscape.

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February Lawn, Garden, and Landscaping Tips 2023

February 10th, 2023 by earthworksjax Landscaping

February Lawn, Garden, and Landscaping Tips 2023

After hard freezes in December 2022 and numerous frost events during January in Jacksonville, we continue to encourage clients to protect tender plants as we transition into Spring with these February lawn, garden, and landscaping tips.

1) Continue protecting plants from freeze and frost damage. Where you live significantly affects the risk of frost and freezing temperatures. While the threat of frost and freezing temperatures vary on average, the last freeze day in Jacksonville is February 15 and January 23 in coastal Jacksonville Beach.

Understand that frost can occur at as high as 37F air temperature when the dew point is 32F or below. Dew point is part of the forecasting available at the National Weather Service.

“When the dew point is below 32 degrees Fahrenheit (0 degrees Celsius), it is known as the “frost point,” referencing the fact that frost will form rather than dew because the temperature is so low,” according to All the Science.

2) Sharpen your mower blades for the new season. Use the mower on its mulch setting, which feeds your soil with organic matter that typically constitutes less than 5% of soil composition and is crucial for biological activity. Feeding the soil with organic matter reduces the need for fertilization by increasing microbial activity and soil structure.
The biological Benefits of Organic Matter in Soil:
– Provides food for the living organisms in the soil.
– Enhances soil microbial biodiversity and activity which can help in the suppression of diseases and pests.
– Enhances pore space through the actions of soil microorganisms. This helps to increase infiltration and reduce runoff.

Top dressing supplementation for the lawn is an excellent approach to increasing organic matter in your soil. Top dressing is available by bag or truckload. And Earth Works Lawn Care offers a combination of aeration and top-dressing services.

3) Keep weeds in your lawn under control by hand pulling or using a pre-emergent herbicide before average temperatures reach 65-70F. As temperatures warm heading into Spring, the threat from the Winter weeds diminishes and is replaced by the emergence of warm-season weeds. In our temperate climate, there is some crossover in the seasonal varieties of lawn weeds.

-Florida perennial weeds include buttonweed, clover, dallisgrass, dandelion, nutsedge, and dollarweed.

-Florida annual weeds include chickweed, crabgrass, beggarweed, pulsey, goosegrass, and spurge.

Weed And Feed products typically include pre-emergents. UF recommends March 1 for the earliest Weed and Feed applications in North Florida. “You will not injure your lawn by waiting to fertilize, but you can certainly injure your lawn by fertilizing too early,” writes Larry Williams, the Residential Horticulture Agent for the UF/IFAS Extension Office in Okaloosa County. Difficulties in avoiding too late applications of pre-emergent herbicides and too early fertilization give some credence to using herbicides and fertilizers separately.

Earth Works Lawn Care division eliminates these concerns for clients with weed spraying and fertilization services.

4) Remember to water your lawn throughout February when receiving less than two weekly rain events. We are under once-per-week irrigation restrictions in Duval County until the second Sunday in March, according to Chapter 366 of the City’s Ordinance Code. However, there are exceptions for new landscaping and no restrictions on hand watering.

The three-year trend of drier-than-normal weather associated with La Nina is forecast to end this year. The latest weather forecast for the ENSO cycle predicts a shift to El Nino, bringing increased rain and flooding in SE USA and a weaker average hurricane season. Address any drainage issues on your property ahead of time.

5) Throughout the Winter months, including February, we continue to encourage the planting of cold-hardy annuals such as alyssum, delphinium, dusty millers, ornamental kale, and cabbage, along with violas that hold up to our coldest temperatures. “Trees and shrubs that will be in bloom include red maple, star magnolia, and spirea,” according to the University of Florida. “Despite the cooler weather, some gardeners can begin to plant warm-season crops, while others should stick to plants that can survive the cold.” Areas around the St. Johns River, its tributaries, and the beaches stay significantly warmer than other inland areas.

6) Continue with regular inspection of houseplants and those brought indoors during the winter, watching out for pests such as Spider mites that form webs along leaf margins. Insecticidal soap, Neem oil, and systemic insecticides provide treatment and protection at different phases of houseplant pest control. Rotate indoor plants to supply them with 360-degree access for inspection and for them to get the best use of available indoor light sources.

Watch for signs of too much or too little water and sunlight. Many plants will turn yellow from too much light or too little water. Fungus gnats and root rot also threaten the health of overwatered plants. Succulents can begin turning purple from various causes, including sudden light and temperature changes, too much light, or the wrong wavelength of certain grow lights will cause problems. If you have an issue with any of your plants or need more lawn, garden, and landscaping tips visit us at Earth Works Gardens.