While more and better spatial information on risk of frost damage is needed, there is no substitute for good local information and monitoring. Most farmers have a good idea about the location of cold spots in their locality. It is definitely worthwhile to consult neighbours before planting sensitive crops at a specific site. Generally, low spots, where cold air ponds, should be avoided. Also, avoid areas where the natural or modified topography dams cold air drainage from the site.
Good Fruit Grower magazine
Because ground fog forms in low spots first, a good rule of thumb is to avoid places where ground fog forms early. Definitely, one should review local topographical maps before planting frost-sensitive crops on high-risk sites. For example, because bloom is late, there is rarely a need for frost protection of walnut orchards in California, but the authors have noted that a few orchards that are planted in cold spots commonly experience damage. This could easily have been avoided by checking local weather records and topographical maps.
Site selection is discussed in more detail later, in the section on passive protection. See the file: "Frost free map. More economic losses are caused by freezing of crops in the USA than by any other weather hazard. In the State of Florida, the citrus industry has been devastated by frost damage on several occasions, resulting in fruit and tree costing billions of dollars Cooper, Young and Turrell, ; Martsolf et al.
Similarly, huge economic losses to other sensitive horticultural crops are frequently observed throughout the world. For example, Hewitt described the effects of freezing on coffee production in Brazil during the s and s. Winterkill of cereals is also a major problem Stebelsky, ; Caprio and Snyder, a, b; Cox, Larsen and Brun, Although the losses to farmers can be huge, there are also many secondary effects on local and regional communities. For example, if there is no fruit to pick, the pickers are unemployed, the processors have little or no fruit, so their employees are unemployed, and, because of unemployment, there is less money in circulation and the local economy suffers.
Consequently, considerable effort is expended to reduce damage. The cost-effectiveness of frost protection depends on the frequency of occurrence, cost of the protection method and the value of the crop. Generally, passive frost protection is easily justified. The cost-effectiveness of active protection depends on the value of the crop and cost of the method. In this book, both passive and active methods are discussed, as well as the economics of protection.
Frost damage to crops has been a problem for humans since the first crops were cultivated. Even if all aspects of crop production are well managed, one night of freezing temperatures can lead to complete crop loss. Except for tropical latitudes, where temperatures seldom fall below the melting point, damage due to freezing temperatures is a worldwide problem. Usually, frost damage in subtropical climates is associated with slow moving cold air masses that may bring nights of hours of subzero temperature Bagdonas, Georg and Gerber, In eastern continental locations, damaging events are typically advective, with weak inversions.
In western continental and marine climates, frost events with calm conditions and stronger inversions are more typical.
The damaging events typically start with advection of cold air followed by a few nights of radiation frost. In temperate climates, frost periods are shorter in duration and occur more frequently than in other climates Bagdonas, Georg and Gerber, For deciduous fruit and nut trees, damaging frost events occur mainly in the spring, but sometimes in the autumn as well. For subtropical fruits, damage to the crops typically occurs during the winter.
In tropical climates, there is normally no freezing except at higher elevations. Therefore, when tropical crops are damaged by cold, the temperature is usually above zero. In temperate climates, damage to grain crops can also occur before booting, under severe conditions, or to flowers even in mild frosts.
For grain farmers, the main response is to plant crops or varieties that are less susceptible to damage e. In any case, the date of planting should be adjusted to the crop, variety and microclimate. Similarly, if subzero temperatures occur too frequently, subtropical crops are preferentially grown in regions with less occurrence of damage. A good example of this is the movement of the citrus industry further south in Florida in response to several severe frosts during the s and s Attaway, At the same time, due to more favourable temperatures, the olive industry is moving northward in Italy where soil and climate factors allow for production of high quality olive oil.
However, this has led to an increase in frost damage to olives during severe winters in , and Rotondi and Magli, Generally speaking, the dates of the last frost occurrence in the spring and the first occurrence in the autumn will determine where particular crops are grown.
For example, many of the deciduous fruit and nut crops tend to be grown in Mediterranean climates because the probability of losing a crop to frost damage is less than in more continental climates. The science of frost protection has mainly developed in response to the occurrence of intermittent damage in relatively favourable climates. If the damage occurs regularly, the best strategy is to grow the crop elsewhere, in a more favourable location.
In some cases, cropping locations change in response to climate change. For example, Attaway noted that prior to orange trees were commonly grown in South Carolina, Georgia and northern Florida, where, because of potential losses to frost damage, people today would not consider commercial production of oranges. He cited several examples of subtropical orchards that had survived up until about , when a severe frost occurred. In fact, there were citations of documents recommending that subtropical fruits be grown in the American southeast to help compete with fruit produced in Mediterranean countries of Europe.
With today's climate, subtropical fruit production would not be considered in these areas. Attaway makes the point that his observations are based on grower experience rather than climatology, but fewer damaging frost events must have occurred during the s for farmers to be producing subtropical fruits where none can be economically produced today.
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The history of frost damage is more sporadic in the Mediterranean climate of California. There have been some major losses from time to time, but the diversity of crops and timing of the frosts leads to less extensive impacts in California. Recently, California suffered two major damaging events in the citrus industry. One occurred in December and the other in December The frost caused the most damage to citrus production since the and frosts Attaway, Interestingly, some regions had little damage, while others were devastated.
Attaway noted that, although the damage to fruit was immense,. We attribute this to the fact that morning lows in the upper 20s and low 30s [i. The December frost was a good example of how hardening can provide protection against frost damage. In Florida, before a cold front passes and drops the air to subzero temperatures, relatively warm temperature often precedes a severe frost. Consequently, the trees are less hardened against frost damage than those exposed to the two California frosts.
Interestingly, Attaway emphasized the inconsistent nature of frost damage that was observed following the frost. For example, within a relatively small region, he noted losses of 70 to 80 percent of the oranges in Ojai Valley, 60 percent to 70 percent losses in Santa Paula Canyon, but only 20 percent losses in the Santa Clara Valley, which is relatively close. This illustrates the site-specific nature of frost damage to crops, especially in hilly and mountainous regions like Ventura County in California.
The December frost was not as bad for California citrus growers as that of ; however, it still is considered one of the major frosts of the twentieth century. The economic losses were high; however, unlike the frost, most growers were able to survive Tiefenbacher, Hagelman and Secora, In their review of the December frost in California's San Joaquin Valley, Tiefenbacher, Hagelman and Secora noted that there was a clear relationship between latitude and damage and latitude and harvesting in anticipation of a frost.
They noted that more northerly orchards suffered more frost damage, but they also harvested considerably earlier than the first frost, which allowed them to survive with less economic loss. His was an interesting answer. A really surprising answer. And an intelligent answer.
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Read what he has to say. You may not be ready for him, but you are not alone. Even the United States Government had to back off when it came to arguing with Ed. And he was totally zonked out of his mind when he did it. He has been a leader in bringing the best cultivation techniques to a mass audience, and he has shown the political courage to stand up to the full force of the federal government, and lived to tell about it.
As Americans first began to grow much of our own marijuana here at home—some with the goal of saving money, some to assure a high-quality product, and others to avoid dealing with the underground market—Ed clearly had a very positive impact on that movement. Any home gardener knows that although anyone can learn to be a successful grower, whether they grow vegetables, flowers, or herbs such as marijuana, gardening is not as simple as planting a seed and watering it occasionally.
It requires a lot of expertise that generally can only be gained from a good book or a more experienced friend. Ed has long been providing accurate and detailed instructions to wannabe farmers so they could turn a good intention into a good crop. Personal cultivation is crucial. It protects consumers from the possibility, once marijuana is legalized, that big corporations take over the market.
Tobacco companies, for instance, already have the land and processing plants available—but the marijuana they may offer could be too expensive, too weak, or otherwise not as high in quality as we have grown accustomed to during the Grow American Movement. Should that occur, we have the ultimate instrument in our hands: we can refuse to purchase their commercially produced marijuana and simply grow our own.
Without the right to cultivate for personal use, consumers could end up with poor choices, poor marijuana, and no real alternatives. He was arrested by the Feds in for managing a nursery that supplied medical patients with starter plants in Oakland, California. He and the city attorney thought he was legally cultivating medical marijuana as an officer of the City of Oakland.
Ed faced a possible year mandatory minimum prison sentence; he refused to discuss a plea agreement. While that strategy might have seemed risky, in the end his courage was rewarded by the judge, who said Ed had justifiably relied on his status with the city, and sentenced him to only one day in jail, with credit for time already served. Ed had survived the best shot the Feds could take, and he is still standing. Ed Rosenthal is the best-known cultivation expert in America. He has written more than a dozen books on the topic; he is politically active and testifies as an expert in state and federal criminal cases.
au.gykimipukopa.ga Over the years, Ed and I have developed a friendship based on mutual respect, and we stay in touch and see each other several times a year at marijuana-related events in different parts of the country. The friendship is largely based on our common appreciation and enjoyment of marijuana, and our shared belief in the importance of making it legal.
I am delighted to give my thanks to Ed Rosenthal for leading the home-grown consumer movement in America, and for bringing us all closer to full marijuana legalization. Keith Stroup, Esq.