Sharpening garden tools and caring for ailing trees: Things to do this week

1. I was sent photos by Charlyn Moltane from Fountain Valley that showed large brown spots on the leaves of a Bacon avocado tree. Initially, I thought the problem was sunburn since avocado leaves are likely to show such spots when temperatures soar as they did this past September, when temperatures were hotter in that month than they had been for 128 years. Yet I then received some photos of the leaf undersides that revealed a colony of minute insects under each brown spot and I realized that the tree is afflicted with avocado lace bugs. While the bugs themselves are one-half inch in size and black in color, numerous black specks that look like grains of pepper are also visible. These specks are lace bug eggs covered for protection with frass (insect excrement) deposited on them by the adults. Treatment for infestation of this insect, as for so many others, involves contact application of insecticidal soaps (M-Pede, Safer) or certain horticultural oils (SunSpray, Volck, Green Light), since they do not inhibit beneficial insects from preying on the pests. Additionally, paying close attention to general practices for ensuring avocado health, such as an adequate water supply when temperatures soar and allowing fallen leaves to remain on the ground for mulch, are always advisable. Application of a fertilizer recommended for avocado trees, easily found at any nursery, at this time of year is also a good idea.

2. Virginia Finkbiner from Glendora wrote about ginkgo trees planted by the city in her neighborhood during the 1950s and ’60s. “We love our ginkgos but the trees overproduce fruit that are extremely smelly when they drop,” she complained. “The whole neighborhood smells like sour milk. They get on everyone’s shoes and are tracked everywhere. Is there anything I can spray to decrease the number of fruit?” There are products such as Florel Fruit Eliminator that are sprayed on trees when they flower to prevent nuisance fruit, pods, or acorns from forming, whether from olive, carob, oak, liquidambar, loquat, ginkgo or many other trees. However, the cost of spraying a large ginkgo tree would be considerable, the window of time for doing so in April is brief, and you may not succeed in spraying all the flowers that would eventually become fruit. Alternatively, the trees could be thinned out so there are not as many fruit-bearing branches, but this would also be costly. I understand the dilemma since no one wants to remove stately trees that are 70 years old but perhaps removing one tree at a time over a period of years, while replacing each tree with a non-fruit bearing male ginkgo, would be a sensible way of moving forward.

3. Joe Ortega, who gardens in Wilmington, submitted a detailed schedule of how he takes care of his poinsettia, which is planted in a south-facing flower bed. It is ten feet tall, ten feet wide, and around 20 years old: “Proper pruning at the right time will produce a beautiful full bush. Cut back in February and feed in April/ May with a 5-10-10 fertilizer. Trim in September and apply a little Vigoro 15-30-15 fertilizer in September and October. The results are a beautiful display in December.” It is worth noting that Ortega’s poinsettia shares a bed with a plumeria since these iconic plants share the same habitat along the west coast of southern Mexico.

4. Winter is downtime in the garden and so this is the right time to oil and sharpen tools as a prelude to spring. Whenever you finish working in the garden, however, there are two practices for extending the life of your tools you might wish to adopt. The first is to take a bucket and fill it with horticultural sand and two quarts of motor oil. Before putting any tool away, plunge your trowel, shovel, or spade into the sand several times. Friction with the sand will add a bit of sharpness to the blades and the oil that will be lightly coated on them will keep away rust. The second practice is to keep a packet of wet disinfectant wipes handy. Using these wipes before putting your tools away will remove dirt as well as clean off any fungal spores or bacterial-laden plant sap that could spread disease.

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5. Take strawberry runners from older plants to replenish or start a new bed of strawberries. Plants more than three years old should be discarded. Prior to planting, incorporate lots of compost or aged manure. Make sure when planting that roots alone, and not leaf bases, are buried beneath the soil surface. Avoid planting strawberries where vegetables in the nightshade family – tomatoes, potatoes, eggplants, or peppers – grew during the last several years since strawberries are susceptible to diseases carried by those crops.

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