Spuds in leafy compost

Spud growing and problems with potatoes

'Green Thumb' gardener gives some tips on problematic potatoes

Since the 2015 Agassiz Fall Fair and Corn Festival celebrates the “Year of the Potato”, a refresher in growing the spud is in order. Potatoes are a fairly easy crop to grow providing the conditions are suitable for this tuber. Acidic friable soil, hilling when 6-8 inches tall, harvesting after blooming and regular watering should produce a healthy yield. Because the soil in the lower mainland tends to be acidic from our high rainfall levels, no lime should be added to the potato bed.

Some frequent problems with potatoes:

Holes in potatoes-there are several types of holes and corresponding causes. Narrow tunneling holes are caused by click beetle larvae, wireworms, which are yellowish-brown shiny hard worms. They are more prevalent in soil where grass had previously been grown. Growing potatoes in containers, raised beds with commercially produced soil or in a soil-less mix of leafy compost, straw, etc., prevents the wireworm invasion. At the present time the Agassiz Research Center has discovered an Agassiz strain of metarhizium, an insect fungal pathogen specific to click beetles and wireworms. When available this pathogen can be added to the soil and greatly reduce the occurrence of the infecting insect.  Small holes just beneath the skin are probably caused by the tuber flea beetle. I am not aware of a safe insecticide for either the flea beetle or the wireworm, however, cutting away the affected part still leaves food for the table. The longer the spuds are left in the ground the more damage will be done. Larger holes are probably caused by slugs. Ferrous phosphate pellets under the leaves or copper tape around the bed are very successful treatments. The pellets are safe for animals.

Hollow heart-spuds growing too quickly either from too much nitrogen or overwatering after a dry spell.

Green and bitter potatoes-exposure to light either while growing, during harvest or in storage causing toxic alkaloids that should be cut away before eating, but can be used for seed.

Knobby spuds-heavy irrigation or rain will cause the tuber to grow in a localized area, forming the knobs. The Russet variety is more susceptible.

Early vine die-down-could be caused by an early variety that has reached maturity or a blight which results in early browning of the leaves and vines. It should be treated with a spray of copper, lime and water as soon as it is noticed.

Heavy foliage and few spuds-too much nitrogen fertilizer or fresh manure application.

Questions and Answers.

Are the mums sold at grocery stores and garden centers hardy?

The chrysanthemums for sale now are grown to fall flower in greenhouses and are not conditioned for our rainy winters. Ideally they need a summer for vegetative and root establishment to survive the winter, so buying in the spring is recommended. They can be kept over in a greenhouse and planted in the spring for fall bloom. If that sounds like too much effort, enjoy them for the season and then say goodbye, as we do with summer annuals.

I always get powdery mildew on my petunias. How can I avoid this?

The mildew is a fungal infection, a disease that is spread by wind-born spores and is difficult to prevent and/or control. Conditions that favor the disease include dry foliage, high humidity, low light, poor air circulation and warm temperatures.  Several treatments have been tried over the years including home remedies. In my search for treatments for powdery mildew, it appears that the most effective home treatment is a spray of 1 part milk to 2 parts water on the new leaves and stems. Affected leaves should be removed before spraying. This should be done once a week and after it rains. Any type of milk will work, whole, 1%, canned or powdered because it is the lactoferrin in the milk that seems to be the active ingredient against the disease. I personally have not tried this remedy, but will next year. Some of the commercial fungicides leave a white residue unbecoming to a beautiful flower.

More questions and comments are appreciated. Please send to news@ahobserver.com