Ask the determined gardener
My pecan leaves have light green knots.
These are caused by Phylloxeran aphids, also affecting grape plants. The balance between host and gall maker usually means the tree will not die, though there may be some economic impact on crops. Gall pests are most effectively treated when the adults are actively laying eggs, as the plant resumes active growth (leaves begin to unfold). Application two to three times over a two-week period is best. Once the gall is formed, the gall maker is protected from contact or systematic insecticides. Pyrethrin, brand name Bug Buster-o, is a contact insecticide with short residual strength.
What can I spray on apple trees for cedar-apple rust?
Cedar-apple rust happens when the fungal genus Gymnosporangium affects the health and vigor of these trees. This can travel from Eastern Red Cedars. If both are in close proximity, the trees can die. On cedar trees young gall balls have circular depressions; next spring, galls develop orange telial horns, resembling worms protruding from gall. On apple trees rust first appears as small greenish yellow spots which gradually enlarge, changing to orange-yellow with borders of red bands. Apply fungicide to apples at blossom and continuing at seven-day intervals until the cedar galls stop spreading spores. Galls on cedar trees need to be removed before they form the “horns.” High resistance to cedar-apple rust exists in Red Delicious, Liberty and McIntosh varieties. For more information, see OSU publication EPP-7611 which can be obtained from your County Extension Office or on line at osufacts.okstate.edu.
How do I kill nut grass (nut sedge)?
In cool season grass, yellow and purple nut sedge can be controlled by hylosulfuron-methyl (Sledgehammer). For warm season grasses Sledgehammer or imazaquin (Image) are effective. In Bermuda grass, apply Penant preemergence in late March to early April. Bentazon is effective on yellow nut sedge with both grass types. For more detailed information, see OSU publications L-441 (warm season grasses) or L-442 (cool season grasses).
What do I need to know about growing tomatoes?
Tomatoes should be grown in full sunlight for the highest yields. Deep, fertile, well-drained soil with plenty of organic matter and a pH around 6.5 is best. Perform a soil test and have it analyzed through your County Extension to determine what additions are needed. Your county extension office can give you detailed instructions on collecting a soil sample. Ideal tomato plants should be 6 to 8 inches tall (6 to 8 weeks’ growth from seed) and dark green with a stocky stem and well-developed root system. For family consumption, 3 to 5 plants per family member should suffice. Plant transplants when the soil temperature is above 60 degrees (find temps on the Oklahoma Mesonet site). Plants should be placed deeper than sown. If leggy, trim off bottom leaves and plant in a trench with the top leaves exposed. New roots will develop along the trunk. Pick varieties with the most resistance to disease (initials F1 and F2, V or others). Side dress plants when first fruit appears and when fruit is at 1/3 growth. One level tablespoon of ammonium nitrate (33-0-0) per plant should provide needed nitrogen. Follow up applications should be made at first ripe fruit and one month later. Tomatoes need one inch of water per week. Dry periods may contribute to blossom end rot, when insufficient levels of calcium are transferred to the fruit growth point. Do not use overhead sprinklers. Pick fruit as it begins to show color and allow to ripen indoors for optimum color development. Tomato crops should not be grown in the same spot more than 3 years. A concentration of disease and viruses will develop with each following crop. This area should not be replanted with tomatoes or similar crops for at least 3 years. OSU Publication F-6012 gives great selection choices and care instructions.
For more gardening information feel free to visit our website at http://oces.okstate.edu/oklahoma or call the OSU Extension office at 405-713-1125.
