From bncraig@peinet.pe.ca Thu Sep 1 11:05:49 1994 Date: Thu, 1 Sep 1994 11:09:47 -0300 (ADT) From: "Brian N. Craig" Subject: P.E.I. POTATO NEWSLETTER -- Vol. 1, No. 1 -- Sep 94 Message-Id: PRINCE EDWARD ISLAND POTATO NEWSLETTER September 1994 Volume 1, No. 1 This is a newsletter to provide information on extension technology that may be useful to the agriculture sector for potato production. The information will provide ideas and information useful to potato production in the North Eastern parts of North America. As this is a Canadian potato newsletter, the information on products will be those registered for use in Canada. Foreign products will be mentioned to provide the agriculture sector with new technology. Please feel free to read the articles and comment on the content. The Newsletter is designed to help individuals to stay up dated on events and technology. Only through comments will the newsletter be able to provide information that will suit your needs. This issue of the Potato Newsletter will focus on top killing, potato harvesting and early storage. From ab4el.com Mon Oct 3 00:00:00 1994 Subject: Potato Vine Killing POTATO VINE KILLING: With potato vine killing, timing and coverage by the desiccant is most important. Rapid vine killing must be avoided to ensure internal tuber discoloration does not take place. Complete vine killing is important to ensure late season aphid populations do not spread viruses into seed potato crops. Also complete vine killing is important to processing potatoes to ensure potato viruses do not spread causing internal quality problems. To ensure a good top kill program for 1994 follow these steps: 1) Calibrate the sprayer - check nozzles, boom height and operating pressure. Recheck your ground speed to ensure that the proper rates of the desiccant is applied. 2) Use clean water - make sure the water used is free of organic material. Organic material will interfere with the effectiveness of the desiccant used. 3) Ensure total coverage - follow the recommendations of the labels of the desiccant you plan to use. Make sure that the water rates suggested on the label are followed. Low water rates will cause difficulties in total coverage. 4) Use spreaders and stickers with your desiccant as recommended on the label. 5) If a second application of a desiccant needs to be applied for total top kill, follow the labelled recommendations for intervals between each application. 6) Be sure to allow the tubers to "mature". After desiccation, do not harvest for at least 2 or 3 weeks. 7) Do not apply desiccants to drought stressed crops as internal discoloration may result. From ab4el.com Mon Oct 3 00:00:00 1994 Subject: Harvest Bruise Reduction HARVEST BRUISE REDUCTION: Potato bruising can cause major problems in the quality of stored tubers. To minimize potato bruising this fall, follow these recommendations: 1) Maximize tuber maturity at time of harvest. The more mature the tuber is the more resistant the tuber is to bruising. 2) Ensure good skin set has taken place after vine killing. 3) Harvest potatoes with a tuber temperature greater than 7.5 oC. Do not harvest potatoes on cold mornings or late evenings when tuber temperature is below 7.5 oC. 4) Regulate the ground speed and chain speeds of harvesters and windrowers to ensure conveyors are filled to their capacity. 5) Potatoes should fall less than 6 inches. Watch the drop from the harvester to the bulk box on the truck. 6) Make sure all hard surface areas are cushioned on the windrower and harvester to protect the moving potato. 7) Bruise check tubers to determine if harvesting operation is minimizing damage to the tubers. The Catechol bruise test is economical and a quick way to check for bruising. 8) Make sure the bin piler at the warehouse is working correctly and piling the potatoes with short drops. From ab4el.com Mon Oct 3 00:00:00 1994 Subject: Catechol Bruise Test CATECHOL BRUISE TEST: The following procedure is a simple way to check tubers for possible bruising: 1) Wash the tuber clean of dirt. 2) Place 10 clean tubers in a small bucket (4-6 litres) with holes in the bottom. 3) Place the bucket of tubers inside a bucket (10 litres) of Catechol Test Solution. 4) Leave the tubers in the Catechol solution for 1 minute. After 1 minute, allow the Catechol solution to drain from the bucket with the holes (just lift the bucket out and it will drain the solution from the tuber bucket). 5) Allow the tubers to stand in a dry place (such as on a burlap bag) for at least 5 minutes. 6) Check the tuber for dark spots. Trim the potato with a potato peeler to determine if the bruise is: "slight", "medium" or "severe". 7) Record the number of tubers in each of the bruising categories. NOTE: When handling Catechol solution and treated tubers, be sure you are wearing rubber gloves to protect yourself from the chemical. WARNING: Do not use potatoes treated with Catechol for food or feed. Keep Catechol containers well labelled and out of reach of children. When assessing the Catechol treated tubers use the ratings: "No Bruising" - no dark areas are visible or no skinning present. "Slight Bruise" - one stroke of the peeler removes all of the visible damage. "Medium Bruise" - two strokes of the peeler removes the damage from the bruised area or cut surface. - four or more slight cuts or bruises (not skinning) are found. "Severe Bruise" - three or more strokes of the peeler removes the damage from the bruised or cut surface. - four or more medium cuts or bruises are found. Catechol Solution: Add 100 grams of catechol into 10 litres of water. Add 25 grams of a surfactant (i.e. dish detergent will work) to the 10 litres of solution. This helps the catechol solution to spread over the tubers. From ab4el.com Mon Oct 3 00:00:00 1994 Subject: Storage at Harvest STORAGE AT HARVEST: When potatoes are harvested, the ventilation in your storage must be operating effectively to ensure that the potato tuber has been cooled and dried. During harvest, potatoes will enter storage: Warm and Dry - the potato tubers should be cooled rapidly down to 13 oC. Try to maintain a relative humidity of 95-100%. The low temperatures will keep diseases on the tuber from causing problems in storage. The high humidity will promote rapid healing of any tuber injury. Also the high humidity helps to minimize the tuber weight loss. Warm and Wet - the potato tubers should be cooled rapidly down to 13 oC. Try to maintain a relative humidity of 95-100%. Under warm conditions make sure the potato tubers are cooled as soon as possible. If the potato tubers are stored with surface water, low humidity and high air volume should be moved through the pile of potatoes. If the surface water is not removed, the potato tubers may suffocate and break down in storage. Cool and Dry - potatoes should be kept at 10 - 13 oC to promote suberization of any damaged surface. If the tuber is below this temperature, bring the storage temperature up to this range to allow for rapid tuber healing. After 3 or 4 days the tubers will suberize, normal ventilation can be continued. Cool and Wet - potato tubers should be warmed to 10 - 13 oC to promote suberization of any damaged surface. With wet tuber surface, the storage humidity should be reduced to 85 - 90% relative humidity. Caution should be taken when high humidity air is circulated around tubers that are cooler than the air. Water will condense on the cooler tubers from the warm humid air. When placing tubers into storage, they must be free of diseases and frost injury. No storage can produce high quality potatoes if the potatoes enter with diseases and frost damage. From ab4el.com Mon Oct 3 00:00:00 1994 Subject: Potato Storage POTATO STORAGE: When storing potatoes, keep in mind that the initial potato quality is extremely important. The potato must be free of diseases and damage before it enters the storage. The management practices placed on the potato crop in the field will determine the quality of potato that will come out of storage later. When potato tubers are placed into storage, make sure the tubers are free of problems such as: wet potato surface, pink eye, blight and frost damage. Excessive soil on tubers can cause storage problems. A good quality potato placed in storage is usually a good quality potato taken out of storage. Tuber temperature and air humidity must be maintained to ensure a quality potato tuber will store well to meet high market standards later. Potatoes are living and will produce heat in the storage. Tuber temperatures must be kept low. Seed, table stock and processing potato tubers require different temperatures to ensure a high quality tuber is available for the market. Relative Humidity is extremely important and must be monitored for in the potato storage. High humidity is needed to minimize the water loss from the tubers (shrinkage). Free water and condensation must be kept from occurring. If water drops onto the potato pile, the potatoes will not hold in storage. When cooling a pile of potatoes down with through-the-pile cooling, the potatoes at the bottom of the pile cools faster than the potatoes at the top of the pile. The rate of cooling a pile depends on: 1) the air flow rate; 2) temperature difference between the inlet air and the potato pile temperature; and 3) the relative humidity of the incoming cooling air. Constant monitoring of temperature and relative humidity at different levels of the storage must be maintained. When storing potatoes make sure the outside air (ventilation air) and air in the storage is not more than 2 oC different. When operating the storage at harvest time, it is best to run the fans in the cool evenings. To cool potatoes down after they have suberized, storage holding temperatures should be dropped down to: SEED = 3.3 oC; TABLE STOCK = 4.5 to 5.0 oC; PROCESSING = 8 oC. Cooling down the stored tubers to the holding temperature should take 3 to 4 weeks. During the storage holding period, ventilation fans should operate about 6 to 8 hours a day . This results in most fans running 3 to 4 times a day to keep the piled potatoes at the proper holding temperatures. From ab4el.com Mon Oct 3 00:00:00 1994 Subject: Author Info Please Forward Potato Newsletter Comments And Requests For Articles To: Brian Craig bncraig@bud.peinet.pe.ca