Agriculture

Berries are Blue

Wednesday, October 5th, 2011

Community Contributed by Glenn I. Teves, County Extension Agent

When it comes to antioxidant content, blueberries are close to the top on the list. As a consequence, everyone is trying to grow them, and Hawaii is no exception.  Blueberry is a potential high value niche-market crop for Hawaii but little has been known about the adaptability of this crop to our sub-tropical conditions until recently. Trials on the Big Island conducted jointly by USDA researchers from Oregon and Hawaii and University of Hawaii College of Tropical Agriculture and Human Resources researchers indicate that a handful of varieties show promise, but there are challenges.

There are many species of Vaccinium or blueberry, with two cousins native to Hawaii called Ohelo, Vaccinium reticulatum from Hawaii and Vaccinium calycinum from Maui. The focus in Hawaii has been to field test crosses of southern hibush types which are a cross between northern highbush from temperate climates and warm species such as Vaccinium darrowii. These types are more tolerant to warm weather and have low chill requirements that allow them to flower in parts of Hawaii.

At least six varieties have been tested on the Big Island since 2004 in three locations. Early results from Waimea indicate that Sharpblue, Misty, Emerald and Jewel performed well, with Sharpblue having the sweetest fruit and Misty having the largest fruits. Fruit size can be manipulated by having good vegetative growth and a robust plant prior flowering. The bigger the flower set, the smaller the fruits. Diseases such as rust and phytophthora can be a challenge. Good drainage can help avoid some root diseases, and dry conditions can help to avoid leaf diseases. Misty and Sharpblue even grew well in Hilo at 250 feet elevation.

The American Society of Horticulture Science Annual Convention held in Kona last week brought key researchers from around the world to present their research, and some of the giants of blueberry research were there. Among them was Dr. Paul Lyrene of University of Florida, a leader in the development of low chill blueberries. He developed four of the six varieties tested in Hawaii, including Misty, Sapphire, Emerald, and Jewel.

Aside from receiving a national award at the meeting for his work, he also presented his latest research on low chill blueberries. His challenge when developing crosses between northern and southern varieties is that you don’t know what parent it will take after. He showed a slide with many confused plants, not knowing if they should grow or flower. Having a lot of vegetation before flowering will allow the plant to carry a larger fruit load.
I was able to talk story with Dr. Lyrene, and he felt that blueberries could be grown successfully in Hawaii. The key was to have a strong harvesting season when the other parts of the world are not in peak production, and in this way you could get top dollar for your product. He also cautioned about a disease called rust that was prevalent in rainy areas that could be a problem in Hawaii.

Blueberry prefers very acid soil in the pH range of 4.0 to 5.2. Sprays of iron help to correct foliar deficiencies, and ground applications of sulfur help to acidify the soil. At the Volcano Research Station blueberries are growing well as a potted plant and will produce handfuls of fruit. One source of disease-free plants is North American Plants.

Going Green Onion

Wednesday, September 28th, 2011

Commnunity Contributed By Glenn I. Teves, UH County Extension Agent

Green onion is an important flavoring and garnish used in many island delicacies from poke to saimin. Known as the Welsh or foreign onion, it’s a member of the Lily family and also known by its Latin name, Allium fistulosum. Green onion is actually a perennial, but we usually grow it as an annual. What distinguishes the true green onion from other onion species is when cut it has a perfectly round leaf, while other onion species have leaves resembling the other phases of the moon. A good green onion will have a light pungency and a pleasant sweetness to it.

Native to Northwest China near the North Korean border and cultivated in China since 200 BC, green onion is still the most important onion of these areas.  It’s grown in many parts of the world as a home garden vegetable. In Oriental medicine, parts of green onion are used to treat fever, inflammation, headaches, stomach aches and diarrhea. Diluted pressed juice is used to control aphids, a common pest of vegetables in China.

Green onion prefers neutral soil of pH 6-6.5 and higher elevations of 600 to over 2,000 feet for optimal growth, although it’s widely adapted. It likes well-drained soil and is very susceptible to water-logging. They have a fairly small root system and don’t compete well with weeds.

Onion thrips are a major pest causing unsightly silver-white lines on the leaves by piercing and rasping the leaf surface. Difficult to control, they thrive in hot weather and live under the leaf sheath where the leaves branch. Part of the life cycle is also spent in the ground. At high populations, the plants lose lots of water from the damage and can desiccate. Using seed instead of divisions and planting in new areas away from old plantings can help to minimize thrips since they can live in planting material. Other occasional pests include the beet armyworm and the serpentine leaf miner.

Diseases include purple blotch, an Alternaria fungus attacking leaves with its characteristic purple blotch on the stalk. The key in controlling many disease problems is to grow a healthy plant, and make sure your nutrition program is well tuned for the different seasons.

By growing them in close spacing, leaves can be kept small. Seed varieties grown in Hawaii include Koba and Fragrance, while many local types are grown by division. Shallots are sometimes grown for it leaves, including the Hawaiian onion or Akakai and the Filipino shallot. Major green onion production areas in Hawaii include the Leeward Coast valleys of Oahu, from Lualualei to Waianae. Growing them in pots in proximity to your kitchen assures a steady and readily available supply of green onion.

Overlooked Vegetables

Wednesday, September 14th, 2011

Community contributed by Glenn I. Teves, UH County Extension Agent.

The August 2011 edition of Consumer Reports featured results of a national survey on how often people ate vegetables, and what kind. Thirty-three vegetables were highlighted. Results show that gender, age, and regional differences dictate what kinds of vegetables are eaten, and how often.

This survey probably has nothing to do with our eating habits in Hawaii, since we’re influenced by both east and west. However, our eating habits are constantly evolving as health challenges dictate what we should be eating. The food experts at Consumer Reports highlighted five overlooked vegetables. I feature three of them plus a few of my own. Most are cooking greens, and they grow well on Molokai in the right season.

The first three are brassicas or mustards. These contain a powerful antioxidant called Glucosinolates, phytonutrients that provide us with unique health benefits because they can be converted into isothiocyanates (ITCs) that have cancer-preventive properties.  Many cultures eat a form of mustards, including African, Indian, Chinese, Japanese, Italian, and Black American Soul Food. Mustards are an essential part of Chinese or local soups.

Pak choy or Pai Tsai, is a mild member of the Chinese mustards. They have white or green swollen stems and large leaves, both dwarf and large types. Stir fried or steamed with a little meat, Pak Choy is an excellent source of vitamins A, C, and K and also provides calcium, f olate, and potassium.  Joi Choi and Mei Qing Choy are two popular varieties. Closely related is Choy Sum, but eaten more for its swollen stems than leaves. Its southern U.S. counterpart, Collard greens has similar nutrients, as well as fiber. Very popular in the south, varieties include Vates, Georgia, Champion, and Green Glaze. They can tolerate hot weather better than mustard greens.

Mustard greens, also grown in the south, have more of a mustard bite and usually grown in the fall months when the cold weather tames its bite. Popular varieties include Green Wave, Tendergreen, and Southern Giant Curled. Our local version is Kai Choy or Chinese mustard cabbage. Two local varieties sold through the UH Seed Store include Waianae Strain and also Hirayama, a white rust resistant strain developed by Chik Hirayama of Kawela. White rust is a destructive fungus with white pustules on the leaves, and humidity helps it to thrive. Another variety, Bau Sin creates a head like head lettuce. Kai Choy is great steamed with a little meat or seafood, and is an important complement in clear or miso-based soup.

The last group is Swiss chard, a cousin to beets. Both have great greens, and are high in iron, magnesium, potassium, and vitamin E. They’re also an excellent source of vitamins A, C and K, and a good source of calcium and fiber. Swiss chard is well adapted to our climate, even hot summers. Varieties include Bright Lights, a beautiful mixture of different color stems, Rhubarb or Ruby Red chard, Fordhook Giant, Rainbow, and Lucullus, a flat-stemmed type popular in Europe. They’re like beets but without the big roots. Beets are also an overlooked vegetable, and the whole plant can be eaten. It scavenges for nutrients deep in the ground. Popular varieties include Excalibur, Merlin, Red Ace, Detroit Dark Red, Ruby Queen, striped-root Chioggia, yellow Touchstone Gold, and heirlooms Bull’s Blood, Crosby Egyptian, and  Burpee’s Gold. Also related to Swiss Chard and Beets is Spinach, another great greens. Leafy greens should be a daily part of our diet.
To order seeds of Kai Choy Chinese and other Hawaii developed vegetables, download ctahr.hawaii.edu/seed/Downloads/Seed%20Order%20Form.pdf.

Stop the Bunchy Top

Tuesday, August 2nd, 2011

Community contributed by Glenn I. Teves, County Extension Agent

Banana Bunchy Top Virus (BBTV) has again reared its ugly head in Ho`olehua. Named after its characteristic choking or bunching of the leaves at the top of the plant, BBTV is the most destructive disease in bananas. Other disease symptoms include a dwarfing of the plants with skinny leaves having yellow or burnt leaf edges bunched together. On the lower portion of the leaves, there are dark green streaks on the mid ribs and also dots and dashes that look like Morse code. The Morse code will move down the mid rib at the attachment to the plant. Fruits are usually stunted, twisted, and distorted.

The hot spots include the new subdivision near Lanikeha, upwind from where it was originally found several years ago, and also around Kualapu`u town. To date, this disease has been confined only to Kualapu`u and Hoolehua. Ginger and heliconia, relatives of banana, are known hosts of this disease but we haven’t seen any diseased plants on Molokai.

The virus is spread by the banana aphid. Just by feeding on an infected plant for 18 hours, the aphid can spread this disease for two weeks. By feeding on a new plant for just two hours, the plant can be infected. Banana plants downwind from the hot spots are especially susceptible to new infections since aphids are not good fliers and will usually float in the wind, with the exception of winged types, called alates, which are usually rare.

The banana variety Chinese or Dwarf Cavendish banana is the most susceptible to this disease. Dwarf Brazilian or Dwarf Apple Banana is more tolerant to it. If you suspect BBTV infected plants in your yard or homestead, do not handle or move the plants. Viruses are systemic; once one plant in a mat is infected, it infects all the plants connected to it. If left untreated, it’s only a matter of time before all the plants in that specific area are infected. The key to controlling the disease is by controlling the banana aphid.

All plants near the infected plant must be treated with insecticides to control the aphid and prevent it from moving from infected to healthy plants. Only after plants are treated can they be moved and destroyed. Complete removal is essential, including killing all plant parts through the use of an herbicide. Treating symptomless plants with insecticides near the hot spot is vital to stop the spread of the disease.  If regrowth occurs from the diseased area, these plants will also have to be treated and destroyed since they still carry the disease.

There is a quarantine prohibiting the movement of banana plants and plant parts, except fruit, from Oahu to all neighbor islands have been imposed. It is only through the vigilance of the community that we’ve been able to keep this disease out of Molokai for so long. For more information on BBTV, check out the UH CTAHR website. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/CFS-BAN-4A.pdf
If you suspect your trees may have the disease call Molokai/Maui Invasive Species Committee at (808) 553-5236 ext. 6585 or (808) 336-0625.