Posts Tagged: breakdown

Satsumas and Navels - Too Late?

There have been some complaints about satsuma mandarin fruit having problems. These are prone to a rind/skin/peel breakdown when the fruit is not picked promptly. It's not clear what the cause is - wet winter, warm winter - but it is less of a problem if the fruit is picked when it is mature. A lot of the time in southern California, satsumas will develop good flavor and sweetness, but for lack of cool weather, they don't turn bright orange, a hallmark of the fruit. So growers will leave the fruit on longer, hoping for color, but the fruit becomes over mature, and more susceptible to breakdown. This weakening of the peel then opens it up to infection by fungi, such as Alternaria. In warm winters, the peel matures more rapidly and is more susceptible. Early maturing varieties like ‘Okitsuwase' are especially prone to breakdown later in the season, since their rind matures earlier. They end up being a mess, as can be seen in the photo below.

Navels can have a similar problem in these winters with erratic rainfall. Common wisdom is you don't irrigate in the winter, right? Wrong. With no, low and widely spaced rain events, the tree roots dry out, and rewet with rain. Navels are building their sugar in the winter and they become suction balls for water as the sugar increases. The fruit will continue to grow as the tree takes up water. When the roots run out of water, and then are suddenly rewetted during this period, the fruit can suck up water so rapidly that the skin cant expand fast enough and will split. So this is what happens with uneven irrigation or rainfall this time of year.  One of those abiotic problems in citrus.

satsuma rind breakdown

split navels

Red Discoloration in My Avocado Flesh

The questions that come in stump many of us, but we often have ways of finding answers.  Here's a recent request and Mary Lu Arpaia's response.  She's one of our Postharvest Physiologist Specialists.

The Question:

"I am an extension specialist in NH, and I work with (mostly temperate!) fruit/veg crops. A consumer has reached out to the NH Division of Public Health here, with concerns about an avocado they purchased. I'm reaching out to you because you have written some outreach materials relating to avocado, and I suspect that you are much more familiar with this crop than we in New Hampshire are. 

Would you have any insights about red discoloration inside an avocado fruit (see attached photo)? It does not look like typical chilling injury to me. Any thoughts would be welcome. Thank you for your time!"

Mary Lu's Response:

"You occasionally see this problem in ripe fruit, especially in lower maturity fruit.

Anyway the best guess is that it is phenolics from the seed coat leaking into the flesh of the fruit.

Not dangerous but the affected flesh may be bitter.  I would cut it out and eat around the discolored flesh which is surface only."

Consumers in far away places often will see problems that we in avocado growing regions may never see. Increasingly though,  the fruit is grown not so close to home and has traveled long distances, been handled by many different people and treated in less than acceptable fashion. So we may see more fruit problems in California as we import more fruit.

avocado red staining

Citrus Endoxerosis: Another Problem Caused by Drought

Recently some 'W. Murcott' mandarins were shown to me.  Brown spots in the core of the fruit.  Another problem caused by drought and lack of leaching rains. Endoxerosis, also called internal decline, yellow tip, dry and blossom end decline is often confused with Alternaria rot which frequently accompanies or follows it.  Internal tissues back of the stylar end break down, dry and become pinkish or brownish in color.  Gum commonly forms in the core and either in or nest to the rind.  Green fruits lose luster and frequently but not always develop a yellow color in circular areas surround the stylar end. The cut fru9i shows the gummy pinkish to brownish mass of partially dried and collapsed tissue. Gumming may even extend into the twig bearing the affected fruit.  When the fruit turns color, the malady is more difficult to detect without cutting.

The cause is believed to be related to water and the physiological conditions within the tree and fruit and temperature conditions in the air and soil influencing transpiration and water stress.  It is suggested therefore that water condones in the soil be kept as favorable for tree heath as possible and pick on time so that they are not over mature.

From: The Citrus Industry, Volume IV, Editor: Walter Reuther, UC Press

In other words, make sure to leach the root zone of accumulated salts from previous irrigations and pray for rain. 

Craig Kallsen in Kern County says he often sees this in young mandarins especially on the south and west sides of the canopy, to the point that growers will not even bother to harvest this fruit until the trees are older.  The fruit just transpires so much water when it's not shaded that the fruit just dries out.

If my Latin serves me right: endo - inside, xeric - dry.  Dry Inside.

endoxerosis 4

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