QUESTION: I have a pine tree that has masses of sap that look like large bubbles or balloons. These occur on small branches near the tips. Some of the needles are dead or dying. What is causing this and what can I do to prevent it?
ANSWER: The mass of sap you see is the result of an insect larvae that is living inside of the blister-like bubble. If you "burst the bubble" you will find a pitch twig moth larvae. There are several species of pitch moths, however the one you have is most likely Petrova comstockiana (Fernald). Eggs are laid singly on the bark of limbs, the hatching larvae tunnel into the bark and cambium region and establish feeding sites. The pine tree exudes pitch and the larvae then uses the pitch to construct a "home" which includes frass or insect droppings. A mature larva is about 25 millimeters long and has a brownish head and light yellow body. Pupation takes place within the pitch mass and adults emerge during the summer months. In some species about half the population requires one year to complete a life cycle; the other half requires 2 years. In the case of this larvae it will feed on one site for one year then move to a new site, usually a branch crotch, and feeds for another year. Thus two years are required for full development from the feeding stage to a pupal stage. Adult moths emerge only in the summer.
CONTROL: Normally there is no need to control these insects. Populations in our area rarely if ever reach economically damaging proportions. If they are really a problem then killing the larvae by pruning out and burning the "bubbles," or open the bubble and impale the larvae on a wire will decrease the population.
SOURCE: Insects That Feed on Trees and Shrubs, 2nd Edition. Warren T. Johnson and Howard H. Lyon. 1991. Page 72.
QUESTION: I have several bites on my face arms and legs. I have a sample of the insects that I think caused these irritations. I have seen an l/8th inch insect with a snout that lays an egg that hatches and borrows up under the skin. Could you please tell me what they are and how to control them?
ANSWER: After examination under a dissecting microscope it was determined that there were no insects in the sample but just pieces of scab and dead skin. There are no known insects that lay eggs on humans which hatch and crawl under the skin. There are skin mites, known as scabies, that can infest humans, but they are microscopic and members of the spider family. They can be controlled using medicated soaps that a dermatologist must prescribe. Also, during summer in the southwest, with low relative humidity and high day time temperatures, using hand lotion will moisturize the skin and relieve the creepy crawly itch that is attributed to insects.
QUESTION: I have some beautiful onions and garlic that I planted last September, but they now have yellow tips on the leaves and then the yellowing progress toward the base of the plant and causes the leaves to curl. Also the place on the bottom of the bulb where the roots attach is rotting. Why is this happening so close to harvest? What can I do about it?
ANSWER: The problem you are experiencing is caused by a soil borne fungus named Fusarium. This disease is called Fusarium Basal Plate Rot and occurs worldwide. The infection can occur anytime during the growing season. The rot progresses from the stem plate up through the storage leaves causing the roots to rot and infects the bulb. Infected bulbs may appear discolored and when cut affected tissues appear brown and watery. Infected garlic shows reddish or reddish purple discoloration on the stem and bulbs early in the growing season with some discoloration on the bulb sheaths at harvest. This disease may also find entry into bulbs more readily when damaged by insects. Optimum temperatures for disease development are when the soil temperatures reach 77-82 degrees F but the fungus can develop at 59 degrees F. Infected bulbs break down during storage.
CONTROL: Rotation from a known infested soil should be for at least four years. Dipping seedlings in a fungicide before transplanting has reduced losses. Control damaging insects and plant resistant varieties are important control measure along with crop rotation.
SOURCE: Compendium of Onion and Garlic Diseases. Howard F. Schwartz and S. Krishna Mohan, Editors. 1995. Page 10.